UNIVERSITY    OF    CALIFORNIA 

COLLEGE    OF    AGRICULTURE 

AGRICULTURAL    EXPERIMENT    STATION 

BERKELEY,    CALIFORNIA 


INVESTIGATIONS  ON  THE  USE  OF  FRUITS 
IN  ICE  CREAM  AND  ICES 

G.  D.  TURNBOW  and  W.  V.  CRUESS 


BULLETIN  434 

September,  1927 


UNIVERSITY  OF  CALIFORNIA  PRINTING  OFFICE 

BERKELEY,  CALIFORNIA 

1927 


Digitized  by  the  Internet  Archive 

in  2012  with  funding  from 

University  of  California,  Davis  Libraries 


http://www.archive.org/details/investigationson434turn 


INVESTIGATIONS  ON  THE  USE  OF  FRUITS 
IN  ICE  CREAM  AND  ICES 

G.  D.  TUENBOWi  and  W.  V.  CRUESS2 


INTRODUCTION 

Methods  of  preparing  fruit  ice  cream  and  water  ices  vary  greatly 
in  different  factories  and  the  quality  varies  correspondingly.  Too 
frequently  manufacturers  use  smaller  proportions  of  fruit  than  are 
required  for  the  best  quality  of  product  and  then  attempt  to  remedy 
the  situation  by  adding  artificial  flavor  and  color. 

These  investigations  were  undertaken  in  order  to  develop  standard- 
ized methods  of  preparation  which  would  improve  the  quality  of 
commercially  prepared  fruit  ice  cream  and  fruit  ices.  Once  in  use, 
such  methods  should  result  in  greater  consumption  of  these  products, 
thus  benefiting  the  fruit  and  ice  cream  industries,  and  the  consuming 
public  as  well, 


HEALTHFULNESS  OF  FRUIT  ICE  CREAMS  AND  ICES 

Fruits  are  an  important  supplement  to  the  milk  products  in  ice 
cream.  Though  they  are  rich  in  vitamins  A  and  B,  milk  products 
usually  contain  only  a  relatively  small  amount  of  vitamin  C.  This 
vitamin,  which  is  particularly  important  for  young  children,  is  found 
in  abundance  in  many  fruits.  Orange  juice  contains  vitamin  C, 
which  helps  to  explain  the  recent  widespread  use  of  orange  juice  in  the 
diet  of  infants  and  young  children.  Vitamin  C  is  also  of  great 
importance  to  the  health  of  adults. 

Most  fruits  contain  acids  such  as  citric,  malic,  and  tartaric,  which 
are  beneficial  to  health,  and  in  addition,  mineral  salts  that  during 
metabolism  give  residues,  basic  in  character,  that  tend  to  counteract 
the  acid  residues  from  a  meat  and  cereal  diet.  The  use  of  a  consider- 
able proportion  of  fruit  in  ice  cream,  therefore,  seems  desirable  from 
the  standpoint  of  increased  healthfulness  of  the  product. 

1  Assistant  Professor  of  Dairy  Industry  and  Associate  Dairy  Technologist  in 
itjie  Experiment  Station. 

2  Associate  Professor  of  Fruit  Products  and  Chemist  in  the  Experiment  Station. 


4  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

Fruit  ices  also  should  be  more  popular,  particularly  as  desserts 
during  the  summer  months.  Their  calorific  (heat  producing)  value 
is  much  less  than  that  of  many  foods,  and  their  natural  acidity  is 
thirst  quenching  and  refreshing.  There  is  no  excuse  for  synthetic 
imitation  fruit  ices — the  cost  of  the  real  fruit  is  low  enough  to  permit 
of  its  generous  use  in  ices. 


FORMS  OF   FRUIT   USED   IN  THE   INVESTIGATION 

Fruits  are  available  to  the  ice  cream  industry  as  fresh,  cold-pack, 
canned,  dried,  and  candied  fruits;  fruit  juices,  fruit  syrups,  concen- 
trates, jams,  preserves,  and  to  a  limited  extent,  fruit  powders.  There 
are  also  fruit  products  specially  prepared  for  the  industry. 

In  the  investigations  reported  in  this  paper  all  of  these  products 
were  used  and  their  relative  desirability  for  use  in  ice  cream  and  ices 
determined. 


THE   COST  OF  VARIOUS    FRUITS    IN    ICE   CREAM 

It  would  appear  on  first  thought  that  fruit  ice  creams  are  more 
costly  and  less  profitable  than  the  plain  ice  cream.  It  must  be 
remembered,  however,  that  the  "colors,"  that  is,  chocolate  ice  cream, 
strawberry,  and  other  fruit  ice  creams  usually  command  a  price 
differential  of  ten  cents  a  gallon.  The  increased  volume  obtained 
from  the  addition  of  the  various  fruits  usually  pays  for  the  cost  of 
the  fruits  and  the  slight  additional  cost  of  manufacture,  so  that  in 
reality  the  fruit  ice  creams,  as  recommended  in  this  publication,  are 
no  more  expensive  per  gallon  than  plain  vanilla  ice  cream. 


INVESTIGATIONS   ON   THE    USE   OF    FRESH    FRUITS    IN    ICE    CREAM 

Investigations  at  the  University  of  California  on  the  use  of  fresh 
fruits  in  ice  cream  have  shown  that  the  present  California  state  legal 
minimum  of  3  per  cent  of  fruit  in  fruit  ice  cream  is  altogether  too 
low.  It  is  impossible  to  prepare  ice  cream  having  a  flavor  character- 
istic of  the  fruit  when  such  a  small  proportion  is  used. 

It  was  also  found  that  the  fruit  must  be  thoroughly  ripe  in  order 
that  it  may  be  broken  up  during  freezing.  The  larger  pieces  of  fruit 
when  too  firm  or  not  finely  ground,  become  hard  and  "icy"  in  the 
cream,  because  their  freezing  temperature  is  so  much  higher  than 
that  of  the  cream. 


BUL.  434]  THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES  5 

Some  fresh  fruits  not  heretofore  used  commercially  in  ice  cream 
were  also  used  successfully  in  our  experiments.  The  best  of  these 
were  fig,  persimmon,  and  avocado. 

Comparison  of  Various  Basic  Mixes.3 — In  the  commercial  manu- 
facture of  ice  cream,  a  basic  mix  is  prepared  containing  butterfat, 
milk  solids-not-fat,  added  cane  sugar,  gelatin,  and  the  entire  mix  is 
pasteurized  and  homogenized.  To  this  is  added  vanilla,  chocolate,  or 
other  flavorings,  or  fruits.  In  these  investigations  two  basic  mixes 
were  compared.  For  convenience,  these  will  be  designated  as  basic 
mixes  No.  1  and  No.  2. 

No.  1  is  of  the  following  composition : 

10.6  per  cent  butterfat 

14.5  per  cent  sugar 

10.5  per  cent  skim  milk  solids 

0.4  per  cent  gelatin 


36.0  per  cent  total  solids. 

No.  2  is  similar  in  composition  to  No.  1  when  first  prepared,  but, 
at  the  time  of  freezing,  specially  prepared  skim  milk  solids  are  added 
to  increase  the  total  solids  to  40  or  41  per  cent.  The  No.  2  mix 
gave  fruit  ice  creams  of  smoother  texture  than  mix  No.  1.  In  the 
formulas  given  in  this  publication,  basic  mix  No.  1  is  to  be  used  unless 
otherwise  specified.  Most  ice  cream  manufacturers  use  a  mix  similar 
to  No.  1.  When  basic  mix  No.  2  is  used,  the  yield  is  increased  so  that 
the  food  solids  per  unit  volume  is  the  same  as  with  No.  1. 

The  experiments  will  be  summarized  in  the  alphabetical  order  of 
the  fruits.  The  principal  points  investigated  with  each  fruit  were 
comparison  of  varieties,  methods  of  preparing  the  fruit  for  use  in  ice 
cream,  and  the  determination  of  best  proportion  of  fruit  to  be  used. 

Fresh  Apricots. — The  effects  on  the  quality  of  the  ice  cream  of 
variety,  maturity,  and  method  of  preparation  of  the  fresh  apricots 
were  studied.  The  Royal  and  Blenheim  varieties  were  found  more 
satisfactory  than  the  Moorpark  and  Tilton,  because  of  their  more 
intense  and  more  uniform  color,  as  well  as  their  more  uniform  ripen- 
ing. The  Tilton  is  too  light  in  color  and  the  Moorpark  ripens  very 
unevenly.  Soft-ripe  fruit  was  found  much  more  satisfactory  than  the 
firm-ripe,  because  it  was  freer  from  green  pieces  and  richer  in  flavor 
and  color. 


3  For  calculation  of  various  mixes  see:  Turnbow,  G.  D.  and  C.  M.  Titus.  An 
accurate  method  of  calculating  ice  cream  mixes.  California  Agr.  Exp.  Sta. 
Hilgardia  1:57-79.     1925. 


6  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

Of  the  various  methods  of  preparing  the  apricots,  the  following 
was  found  best.  The  well  ripened  apricots  were  halved  and  pitted, 
but  not  peeled.  They  were  then  ground  to  medium  fiineness  in  a  food 
grinder.  To  each  8  pounds  of  pulp  was  added  2  pounds  of  sugar. 
This  mixture  was  boiled  three  to  five  minutes. 

Uncooked,  ground  apricot  pulp  was  unsatisfactory  because  the 
individual  pieces  became  hard  and  icy  in  texture  when  the  ice  cream 
was  frozen.  Apricot  pulp  containing  much  more  than  20  per  cent  of 
added  sugar  depressed  the  freezing  point  of  the  ice  cream  unduly, 
causing  it  to  be  soft  under  ordinary  storage  conditions. 

In  order  to  obtain  sufficient  flavor  and  color  in  the  finished  product, 
it  was  found  necessary  to  add  about  15  per  cent  of  the  pulp,  prepared 
as  previously  described,  to  the  ice  cream  mix ;  that  is,  about  8  pounds 
to  45  pounds  of  basic  mix.  While  as  little  as  10  per  cent  of  the 
prepared  fruit  imparted  a  recognizable  apricot  flavor  to  the  cream,  the 
flavor  was  too  faint  to  render  the  product  distinctive. 

The  following  procedure  is  recommended :  Use  soft-ripe  Royal  or 
Blenheim  apricots.  Cut  in  half  and  pit.  Grind  to  medium  fineness. 
To  8  pounds  of  pulp,  add  2  pounds  of  sugar.  Boil  three  to  five 
minutes  and  cool.  To  45  pounds  of  unflavored  ice  cream  mix,  add 
8  pounds  of  the  prepared  apricot  pulp  and  freeze  in  the  usual  manner 
to  100  per  cent  yield ;  that  is,  to  about  11%  gallons. 

Fresh  Avocados. — Several  ice  cream  manufacturers,  who  have 
been  persuaded  to  prepare  avocado  ice  cream  commercially,  have  found 
that  there  is  a  potential  market  for  limited  quantities  in  the  high  class 
hotel  and  restaurant  trade.  When  production  of  avocados  shall  have 
increased  sufficiently  to  make  the  cull  fruit  available  at  the  price  of 
other  fruits  used  in  ice  cream,  there  should  be  a  good  demand  for 
avocado  ice  cream  as  a  "special"  for  the  regular  trade,  because  the 
product  is  of  very  attractive  appearance  and  of  rich,  pleasing  flavor. 

It  was  found,  as  with  other  fruits,  that  thoroughly  ripe  fruit  (in 
this  case,  soft-ripe)  was  best  for  the  purpose.  Heating  even  to  175- 
180°  F  was  found  to  injure  the  flavor  seriously.  On  standing  in  the 
air,  avocado  pulp  soon  darkened  through  oxidation.  The  best  results 
were  obtained  by  grinding  the  peeled  and  pitted  fruit  to  a  fine  paste 
and  adding  immediately  about  18  per  cent  of  it  by  weight  to 
unflavored  ice  cream  mix  (that  is,  10  pounds  of  the  fruit  to  45  pounds 
of  mix),  and  freezing  in  the  usual  manner  to  100  per  cent  yield,  or 
to  about  12  gallons. 

Avocado  ice  cream  is  pale  green  in  color,  smooth  in  texture,  and 
resembles  pistachio  nut  ice  cream  in  flavor  as  well  as  in  appearance. 


BUL.  434]  THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES  7 

Fresh  Bananas. — While  the  banana  is  not  a  California  fruit,  for 
the  sake  of  completeness  it  was  included  in  the  fruit  ice  cream  experi- 
ments. It  was  found  unnecessary  to  reinforce  the  banana  flavor  with 
artificial  flavor,  provided  sufficient  fruit  was  used.  The  following 
recommended  procedure  is  the  result  of  trials  made  with  commercial- 
sized  lots  of  ice  cream  by  the  Dairy  Division  of  the  University  of 
California: 

Peel  and  grind  enough  thoroughly  ripe  bananas  to  give  3  to  4 
pounds  of  ground  fruit.  Add  to  45  pounds  of  unflavored  mix  and 
freeze  to  100  per  cent  yield.  A  small  amount  of  yellow  color  may  be 
added  if  desired. 

Fresh  Blackberries. — These  gave  an  ice  cream  of  rather  unattrac- 
tive color,  and  not  very  distinctive  in  flavor.  Fresh  blackberries  are 
recommended  for  use  in  water  ices  rather  than  in  ice  cream. 

Fresh  Cherries. — Because  of  the  popular  prejudice  against  the 
mixing  of  fresh  cherries  and  cream,  the  fresh  cherries  were  not  used 
in  these  investigations.  See  experiments  with  maraschino  cherries  on 
page  18. 

Fresh  Figs. — Fresh  figs  are  obtainable  at  moderate  cost  in  August 
and  September  in  the  interior  valleys  of  California.  Although  not 
generally  known,  fig  ice  cream  possesses  unusually  pleasing  flavor  and 
general  quality,  and  should  prove  popular. 

Three  varieties,  the  Black  Mission,  Calimyrna,  and  Kadota,  were 
compared.  The  Kadota  and  the  Mission,  because  they  lack  in  flavor 
and  have  very  small  seeds,  were  not  as  satisfactory  as  the  Calimyrna. 

While  fairly  good  results  were  obtained  by  adding  the  finely 
ground,  unsweetened,  and  uncooked  figs  to  the  mix,  there  was,  as  with 
apricots,  a  tendency  for  the  larger  pieces  of  pulp  and  skin  to  treeze 
to  an  icy  consistency  and  to  cause  the  cream  to  be  rough  in  texture. 
Much  better  results  were  obtained  by  cooking  the  ground  fruit  with 
sugar  before  adding  it  to  the  mix. 

About  15  per  cent  by  weight  of  the  cooked  fresh  figs  was  necessary 
to  give  a  characteristic  flavor  and  appearance  to  the  cream;  20  per 
cent  gave  a  better  product  than  did  15  per  cent. 

The  following  procedure  is  based  on  these  experiments :  Use  soft- 
ripe  figs.  Cut  off  the  stems.  Grind  the  fruit  to  medium  fineness.  To 
7  pounds  of  figs  add  iy2  pounds  of  sugar.  Boil  three  to  four  minutes. 
Cool  and  use  with  45  pounds  of  ice  cream  mix.  Freeze  to  100  per  cent 
yield;  that  is,  to  about  liy2  gallons. 


8  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

Fresh  Oranges. — Although  orange  ice  is  much  better  known  and 
more  popular  than  orange  ice  cream,  there  is  a  considerable  demand 
for  the  latter.  Most  published  formulas  recommend  too  small  a  pro- 
portion of  orange  juice. 

The  best  method  of  extracting  the  juice  was  found  to  be  by 
"burring"  the  halved  oranges  on  a  rapidly  revolving  metal  or 
porcelain  cone.  Small  juice  extractors  having  such  a  cone  are  in 
common  use  in  soda  fountains.  Pressing  the  whole  or  crushed  fruit 
gave  a  juice  of  less  desirable  flavor  and  with  too  little  of  the  highly 
colored  pulp.     See  figure  4. 

The  addition  of  some  lemon  juice  and  sugar  was  found  desirable. 

The  following  procedure  is  recommended :  Cut  the  oranges  in  half 
and  extract  the  juice  on  a  revolving  cone.  Strain  through  a  screen  to 
remove  seeds  and  coarse  pieces  of  pulp  and  skin.  To  3  quarts  of 
orange  juice,  add  1  pint  of  lemon  juice  and  3  pounds  of  sugar.  For 
3  quarts  of  juice,  about  3*4  dozen  oranges  of  average  size  are 
required;  for  one  pint  of  lemon  juice,  1  dozen  lemons  are  required. 
Dissolve  the  sugar  by  stirring.  Add  to  45  pounds  of  ice  cream  mix. 
Add  a  few  drops  of  orange  oil  (approximately  8  drops)  and  a  small 
amount  of  orange  color. 

Orange  oil  stored  at  room  temperature  soon  becomes  "rancid" 
or  "  turpentiney "  in  odor  and  flavor  because  of  oxidation  and  other 
changes  in  the  terpenes.  To  prevent  this  very  undesirable  change,  the 
oil  should  be  stored  at  about  32°  F.  Only  small  quantities  should  be 
purchased,  so  that  it  may  be  used  before  it  spoils  in  flavor. 

Fresh  Peaches. — Some  varieties  of  peaches  were  more  suitable  than 
others  for  use  in  ice  cream.  The  common  canning  varieties  of  cling- 
stones lacked  flavor  and  required  prolonged  cooking  to  make  them  soft 
enough  for  use.  The  common  drying  and  shipping  freestones,  such 
as  the  Muir,  Crawford,  Lovell,  and  Elberta,  also  lacked  flavor; 
nevertheless,  they  were  superior  to  the  canning  clingstones  in  texture 
and  flavor.  The  Lovell  was  best  but  was  not  so  satisfactory  as  the 
highly  flavored,  soft  textured,  early  table  peaches  that  were  purchased 
in  the  open  market  under  the  name  of  Strawberry  and  Carmen.  These 
gave  a  cream  of  pronounced  peach  flavor. 

With  the  other  varieties,  i.e.,  Muir,  Crawford,  Lovell,  etc.,  it  was 
found  necessary  to  use  a  relatively  large  proportion,  about  20  per 
cent  by  weight,  of  fruit  in  order  to  obtain  a  cream  readily  recognized 
as  peach. 


BUL.  434]  THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES  9 

Cooking  with  sugar  before  the  fruit  was  added  to  the  ice  cream 
mix  prevented  the  formation  of  ice  crystals  after  freezing. 

The  following  procedure  is  recommended :  Use  soft-ripe,  freestone 
peaches,  such  as  the  Lovell  or  a  soft  easily  peeled  table  variety.  To 
peel,  dip  in  boiling  water  for  30  to  60  seconds  or  steam  for  one  to 
two  minutes.  Chill  in  cold  water  and  life  the  skins  from  the  fruit. 
Remove  pits.  Grind  the  fruit.  To  10  pounds  of  the  pulp,  add  3 
pounds  of  sugar.  Boil  gently  three  to  five  minutes  and  cool.  Add 
to  45  pounds  of  unflavored  ice  cream  mix.  If  yellow  fruit  is  used, 
no  added  color  is  needed.  Freeze  to  about  100  per  cent  yield ;  that  is, 
to  about  121/2  gallons. 

Fresh  Bartlett  Pears. — Bartlett  pears  are  plentiful  and  low  priced 
during  the  season,  July  15  to  September  1,  and  are  obtainable  from 
cold  storage  until  January  1.  They  were  found  only  fairly  satis- 
factory for  ice  cream.  Crushed  or  ground  fresh  pears  darkened  very 
rapidly.  On  this  account  they  were  unsatisfactory  unless  heated  to 
destroy  the  enzyme  responsible  for  the  darkening.  Like  the  canning 
and  drying  varieties  of  peaches,  Bartlett  pears  were  somewhat  lacking 
in  flavor;  about  20  per  cent  by  weight  had  to  be  used.  The  flesh  being 
firm,  preliminary  cooking  to  soften  the  texture  was  found  necessary. 

The  following  procedure  is  recommended :  Use  thoroughly  ripe 
(but  not  overripe)  Bartlett  pears.  Peel,  cut  in  half,  and  grind  fine. 
To  10  pounds  of  the  pulp,  add  2%  pounds  of  sugar.  Boil  about  five 
minutes.  Cool  and  use  with  45  pounds  of  mix,  freezing  to  100  per 
cent  yield  or  to  about  12  gallons.  A  small  amount  of  yellow  color 
improves  the  appearance. 

Fresh  Persimmons. — At  the  request  of  the  Southern  Counties 
Farm  Bureau  Federation  of  California,  persimmons  were  used  experi- 
mentally for  the  preparation  of  various  products,  among  them  per- 
simmon ice  cream.  Soft,  ripe  Hachiya  persimmons  were  peeled,  the 
stems  were  removed,  and  the  fruit  was  ground  to  a  jam -like  consist- 
ency. One  pound  of  sugar  was  added  to  each  3  pounds  of  pulp.  The 
sweetened  pulp  was  added  to  basic  ice  cream  mix  to  the  extent  of  about 
18  per  cent  by  weight ;  that  is,  about  10  pounds  to  45  pounds  of  mix. 
These  quantities  yielded  about  12  gallons  of  finished  cream. 

The  resulting  cream  was  a  rich  golden  yellow  in  color  and  had  a 
pronounced  but  very  pleasing  flavor,  smooth  texture,  and  good  keep- 
ing quality  in  the  hardening  room.  It  is  believed  that  this  ice  cream 
affords  a  very  good  outlet  for  surplus  persimmons. 

Fresh  Raspberries. — Raspberries  behave  like  strawberries  in  ice 
cream.     Four  pounds  of  the  washed  and  crushed  or  ground  berries 


10  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

added  to  45  pounds  of  mix  containing  one-half  the  amount  of  vanilla 
flavor  used  in  vanilla  ice  cream  has  been  found  to  give  a  very  good 
raspberry  ice  cream.  A  small  amount  of  added  color  is  usually  neces- 
sary to  give  a  cream  of  the  color  expected  by  the  consuming  public. 

Fresh  Strawberries. — The  experiments  show  that  the  minimum 
legal  limit  is  altogether  too  low  for  strawberries  as  well  as  for  other 
fruits.  Not  less  than  6  per  cent  of  strawberries  should  be  used.  All 
varieties  of  strawberries  are  not  equally  desirable  for  use  in  ice  cream. 
The  Banner,  which  is  the  most  common  variety  grown  in  this  state, 
lacks  color,  particularly  near  the  center  of  the  berry.  Furthermore, 
the  berries  are  often  hollow.  The  highly  colored  varieties  that  are 
solid  in  texture  and  red  in  color  to  the  core  are  to  be  preferred.  The 
Marshall  has  been  used  by  the  Dairy  Industry  Division  and  has  been 
found  excellent  for  the  purpose.  It  can  usually  be  obtained  directly 
or  by  dealers  from  a  few  growers  in  the  important  berry  growing 
districts  in  California,  but  is  difficult  to  obtain  on  the  open  market. 
The  Ettersberg  and  Trebla  are  also  desirable  preserving  varieties 
grown  in  the  Pacific  Northwest  and  should  be  equally  as  good  as  the 
Marshall  for  use  in  ice  cream. 

The  following  procedure  is  recommended :  Hull  and  wash  thor- 
oughly ripe,  well  colored  berries  and  crush  or  grind  them.  Add  4 
pounds  of  the  berries  to  45  pounds  of  ice  cream  mix  containing  one- 
half  the  amount  of  vanilla  flavoring  used  in  vanilla  ice  cream.  Freeze 
to  100  per  cent  yield  or  to  about  10%  gallons.  Four  pounds  of  berries 
correspond  to  about  8  per  cent  fruit  by  weight. 

A  small  amount  of  color  may  be  added;  no  artificial  flavor  is 
required  and  should  not  be  added,  as  it  very  seriously  detracts  from 
the  natural  berry  flavor. 


INVESTIGATIONS   ON  THE   COLD-PACKING   OF    FRUITS   AND   THEIR 

USE   IN   ICE  CREAM 

Strawberries,  raspberries,  and  blackberries  are  stored  at  freezing 
temperatures  in  commercial  quantities  for  the  fruit  preserve  and  ice 
cream  industries.  Previous  investigations4  have  demonstrated  that 
most  of  the  berries  and  deciduous  fruits  grown  in  California  can  be 
preserved  with  practically  all  of  their  fresh  flavor  and  color,  when 
properly  prepared  and  stored  in  sealed  containers  at  15°  F  or  less. 


4  Cruess,  W.  V.,  E.  L.  Overholser,  and  S.  A.  Bjarnason.  Storage  of  perish- 
able fruits  at  freezing  temperatures.  California  Agr.  Exp.  Sta.  Bui.  324:25- 
43.     1920. 


Bul.  434] 


THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES 


11 


While  freezing  storage  softens  the  fruit  texture,  this  softening  in  no 
way  injures,  but  rather  improves,  the  value  of  the  fruit  for  use  in 
ice  eream. 

In  connection  with  the  investigations  on  the  use  of  fruits  in  ice 
cream,  experimental  lots  of  various  fruits  were  prepared  and  stored 
at  low  temperatures  both  at  Davis  and  at  Berkeley. 

Determination  of  the  Bate  of  Cooling.5 — In  commercial  cold  storage 
establishments,  berries  and  crushed  fruits  packed  in  50-gallon  barrels 


70 


k  oo 
to 


JO 


§40 

i 

10 


fO-GaL 

K*=>^> 

^<^„ 

1 

n 



£4 


48 


72  96 

Hours 


120 


168 


Fig. 


1. — Relative  rates  of  cooling  for  crushed  fruit  in  various 
size  containers. 


and  placed  at  once  in  freezing  storage  sometimes  undergo  fermentation 
before  the  fruit  cools  sufficiently  to  prevent  yeast  growth  and  activity. 
In  order  to  obtain  accurate  information  on  the  rate  of  cooling  of 
crushed  fruit  under  practical  conditions  a  10-gallon  keg,  a  5-gallon 
keg,  and  a  No.  10  can  (slightly  less  than  1  gallon  capacity)  were  filled 
with  crushed  fruit  at  room  temperature.  They  were  fitted  with 
resistance  thermometers  and  placed  in  the  freezing  storage  room  in 
Ililgard  Hall  at  a  temperature  varying  from  about  1°  F  below  zero 
to  about  5°  F  above  zero. 

By  means  of  an  instrument  outside  the  cold  room,  but  connected 
to  the  resistance  thermometers  by  suitable  wire  leads,  the  temperature 
at  approximately  the  center  of  each  container  was  read  at  frequent 
intervals,  with  the  results  illustrated  in  figure  1. 


5  Conducted  in  cooperation  with  George  Marsh,  former  student  assistant  in 
Fruit  Products.  From  Cruess,  W.  V.  Utilization  of  surplus  plums.  Calif.  Agr. 
Exp.  Sta.  Bull  400.     192G. 


12  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

The  No.  10  can  cooled  very  quickly,  reaching  32°  F,  the  freezing 
point  of  water,  in  less  than  five  hours;  the  5-gallon  keg  reached  32°  F 
in  a  little  less  than  sixteen  hours,  and  the  10-gallon  keg,  in  about 
thirty  hours.  At  about  26°  F  cooling  in  all  three  containers  became 
very  slow  for  about  a  twenty-four  hour  period  in  the  kegs  and  for 
about  eight  hours  in  the  No.  10  can.  This  represents  the  freezing  of 
the  fruit  to  a  solid  piece  of  ice  with  consequent  retardation  of  heat 
transfer.  At  the  time  of  freezing,  the  temperature  of  the  entire 
contents  of  the  containers  probably  became  that  of  the  freezing  tem- 
perature of  the  fruit,  about  26°  F.  The  thermometers  being  located 
at  the  centers  of  the  containers  would  not  register  any  further  change 
until  the  "cold"  had  again  penetrated  to  the  centers,  causing  the 
temperature  again  to  drop. 

If  the  fruit  in  the  10-gallon  keg  had  been  in  poor  condition,  that 
is,  badly  bruised  and  infected  with  yeast  before  packing,  it  would 
probably  have  fermented  for  several  hours  before  reaching  a  tempera- 
ture low  enough  to  arrest  fermentation.  In  50-gallon  barrels,  the 
margin  of  safety  is  of  course  still  less. 

Comparison  of  Open  and  Sealed  Containers. — In  commercial  prac- 
tice, berries  for  making  preserves  and  ice  cream  are  stored  in  open 
crates  or  baskets  at  a  freezing  temperature,  or  are  crushed  in  open 
barrels.  Both  of  these  methods  of  storage  were  found  objectionable. 
In  open  baskets  or  crates,  the  fruit  lost  much  of  its  flavor  and,  on 
thawing,  tended  to  become  brown  in  color.  In  open  containers  such 
as  barrels  they  absorbed  flavor  from  other  products  stored  in  the  same 
room  with  the  fruit. 

Number  10  fruit  cans,  enameled  inside,  proved  very  satisfactory 
and  inexpensive  containers.  A  small  hand-power  can  sealer  was  used 
in  sealing  the  cans. 

Recently,  the  can  manufacturers  have  produced  for  the  cold-pack 
industry  a  special  5-gallon  can  fitted  with  a  6-inch  friction  seal  open- 
ing in  the  top  and  coated  inside  and  out  with  a  protective  enamel 
that  prevents  rusting  and  reduces  corrosion.  This  container  can  be 
recommended  to  those  ice  cream  manufacturers  who  wish  to  store  fruit 
for  their  own  use.  No  equipment  is  needed  for  sealing  the  can,  and 
with  proper  care  it  can  be  used  for  several  seasons.  It  is  illustrated 
in  figure  2. 

Barrels  are  not  so  satisfactory  as  cans  for  the  following  reasons. 
When  opened  for  use,  only  a  small  portion  of  the  contents  of  the 
barrel  is  used;  the  remainder  stands  in  the  open  barrel  usually  for 
several  weeks  before  all  of  it  is  used.     It  oxidizes  near  the  surface, 


Bul.  434] 


THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES 


13 


turning  brown,  loses  flavor,  and  usually  acquires  a  "cold  storage" 
odor  and  flavor.  The  contents  of  a  No.  10,  or  of  a  5-gallon  can,  are 
used  at  once  or  within  a  day  or  two  after  opening,  and  consequently 
have  no  opportunity  to  deteriorate  greatly  in  quality. 

Comparison  of  Storage  in  Syrup  and  with  Dry  Sugar. — Cold-pack 
berries  for  the  trade  are  usually  packed  with  sugar.  In  these  experi- 
ments, various  fruits  were  packed  in  water  in  sealed  containers,  with 
syrups  of  various  sugar  concentrations;  and  with  various  proportions 
of  dry  sugar.     Berries  were  found  most  satisfactory  for  use  in  ice 


Fig.  2. — Five-gallon  enameled  can  for  cold-packing  of  fruits. 

cream  when  packed  with  half  their  weight  of  sugar ;  that  is,  1  part  of 
sugar  by  weight  to  2  parts  of  berries.  Crushing  the  berries  before 
packing  improved  them  for  use  in  ice  cream.  With  less  sugar,  the 
flavor  was  not  so  well  retained ;  with  more,  the  fruit  was  too  sweet  and 
gave  a  soft  cream,  because  the  excessive  sugar  content  depressed  the 
freezing  point  unduly.  In  water  and  in  syrups,  the  berries  tended  to 
float  on  thawing,  giving  a  large  volume  of  syrup ;  and  the  color  tended 
to  diffuse  into  the  liquid,  causing  the  berries  to  be  too  pale  in  color. 

Crushed  apricots,  peaches,  figs,  persimmons,  avocados,  and  plums 
were  most  satisfactory  when  mixed  with  1  part  of  sugar  to  2  of  fruit 
and  packed  in  sealed  containers. 

Sliced  fruits  and  whole  figs  were  best  packed  in  a  syrup  of  medium 
density;  that  is,  of  about  50  per  cent  sugar  content,  made  of  equal 
parts  sugar  and  water,  and  stored  in  sealed  containers. 


14  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

Effect  of  Length  of  Storage. — Strawberries,  loganberries,  black- 
berries, raspberries,  and  apricots  have  retained  their  flavor  perfectly 
in  sealed  cans  at  zero  to  15°  F  for  more  than  three  and  a  half  years. 
Peaches  after  one  year's  storage  had  acquired  a  slight  bitter  almond 
flavor,  but  were  still  satisfactory  for  most  purposes. 

Procedure  Recommended  for  Cold-packing  Various  Fruits. — The 
following  methods  of  preparing  and  cold-packing  various  fruits  are 
recommended : 

(a)  With  berries,  all  varieties:  Stem,  sort  and  wash  thoroughly 
ripe  berries.  Pack  2  parts,  by  weight,  with  1  part,  by  weight,  of  sugar 
in  enamel-lined  friction  top,  5-gallon  cans  or  in  enamel-lined,  No.  10 
fruit  cans,  jolting  the  cans  vigorously.  In  5-gallon  cans  fill  to  about 
1%  inches  of  top.    Seal  and  store  at  once  at  zero  to  15°  F. 

(b)  With  apricots,  avocados,  persimmons,  and  peaches:  Use  soft- 
ripe  fruit.  Pit  the  apricots;  peel  and  pit  the  avocados  and  peaches; 
pit  the  persimmons,  seedless  preferred.  Grind  the  fruit.  Add  1  pound 
of  sugar  to  each  3  pounds  of  pulp  and  seal  and  store  as  directed  for 
berries. 

(c)  With  fruit  juices:  Extract  the  juice  from  grapes  and  berries 
by  crushing  and  pressing ;  from  citrus  fruits,  by  a  revolving  cone.  To 
each  gallon  of  juice,  add  3  pounds  of  sugar.  Fill  jugs  or  5-gallon 
bottles  about  three-quarters  full.  Cork  and  store  at  zero  to  15°  F. 
Do  not  fill  glass  containers  too  full,  or  they  will  burst  because  of  the 
expansion  of  the  juice  on  freezing.  Juices  prepared  in  this  manner 
and  stored  in  sealed  containers  at  zero  to  10°  F  have  retained  their 
fresh  flavor  and  color  in  tests  for  more  than  four  years. 

Using  Cold-pack  Fruits  in  Ice  Cream. — It  was  found  necessary  to 
thaw  the  frozen  fruits  before  using  in  order  that  the  ice  cream  would 
be  free  of  large  ice  crystals.  The  fruit  was  then  ground  or  crushed 
and  used  in  the  same  proportions  and  in  the  manner  described  for  the 
fresh  fruits. 

INVESTIGATIONS  ON  THE  USE  OF  CANNED  FRUITS  IN  ICE  CREAM 

While  canned  fruits  are  not  very  generally  used  in  ice  cream  at 
present,  several  varieties  were  used  in  our  experiments  and  gave 
excellent  results.  They  are  much  less  costly  than  the  same  fruits 
specially  prepared  for  the  ice  cream  industry  and  are  equally  as  good 
or  better  for  the  purpose. 

Comparison  of  Different  Varieties  of  Canned  Fruits, — Com- 
mercially canned  peaches,  pears,  pineapple,  apricots,  and  figs  were 


BUL.  434]  THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES  15 

used  in  the  preparation  of  ice  cream.  It  is  already  well  known  that 
commercially  canned  crushed  pineapple  is  satisfactory  for  this  pur- 
pose. The  only  work  done  with  pineapple,  therefore,  was  to  determine 
what  treatment  should  be  given  it  before  adding  to  the  mix. 

Canned  peaches  lacked  flavor,  although  when  20  per  cent  or  more, 
by  weight,  was  added  to  the  mix  (about  11  pounds  to  45  pounds  of 
mix),  a  fairly  satisfactory  ice  cream  resulted.  The  freestone  varieties 
possessed  somewhat  more  flavor  than  the  clingstone  varieties. 

Pears  gave  a  satisfactory,  although  not  unusually  distinctive  ice 
cream,  when  sufficient  fruit,  about  20  per  cent  by  weight,  was  used. 

Canned  apricots  gave  excellent  results,  the  canned  fruit  being 
equal  in  every  way  to  the  fresh.  Some  ice  cream  makers  already  use 
canned  apricots,  although  the  use  of  specially  prepared  crushed 
apricots  is  more  common. 

Canned  figs  were  found  to  be  very  desirable  for  use  in  ice  cream 
and  cheaper  than  the  fresh  fruit,  if  the  proper  grade  of  canned  figs 
is  used. 

Comparison  of  Different  Grades  of  Canned  Fruits. — There  are  five 
commercial  grades  of  California  canned  fruits.  These  are:  Fancy, 
which  consists  of  fruit  of  the  highest  quality,  canned  in  a  heavy  syrup ; 
Choice,  fruit  of  excellent  quality  canned  in  medium  heavy  syrup ; 
Standard,  fruit  of  medium  quality  canned  in  medium  light  syrup ; 
Seconds,  fruit  of  second  quality  canned  in  very  dilute  syrup ;  and 
Water  or  Pie,  sound  fruit  that  is  overripe,  or  trimmed,  or  slightly 
blemished,  canned  without  added  syrup  or  in  water  only. 

The  different  grades  of  the  more  important  canned  fruits  were 
compared  experimentally  for  use  in  ice  cream.  Unexpectedly,  the  pie 
grade  was  found  much  superior  to  the  other  grades  for  use  in  ice 
cream,  principally  because  there  was  much  more  fruit  of  this  grade 
to  each  can  and  much  less  waste  liquid.  This  grade  is  much  lower  in 
price  than  the  other  grades  and  at  present  is  the  most  difficult  grade 
for  the  canner  to  sell.  It  may  be  purchased  by  the  case  of  six,  No.  10 
cans,  direct  from  canneries,  or  from  canned  food  brokers,  jobbers,  and 
wholesalers. 

There  are  two  classes  of  pie  grade  canned  fruits:  that  known  as 
' '  solid  pack, ' '  and  that  known  as  ' '  water  pack. ' '  The  ' '  solid  pack ' '  is 
by  far  the  better  for  use  in  ice  cream  and  should  be  specified  when 
ordering. 

If  ordered  in  advance  of  the  fruit  season,  some  canners  will  pre- 
pare canned  puree  from  apricots,  peaches,  and  pears.  This  product  is 
ready  to  use  and  is  not  costly.    In  experiments  conducted  on  a  semi- 


16 


UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 


commercial  scale  by  P.  F.  Nichols  of  the  Fruit  Products  Laboratory, 
it  was  found  that  an  excellent  quality  of  canned  crushed  pears  can  be 
made  by  commercial  canners  from  pie  grade  pears  by  mixing  the 
crushed  fruit  with  1  part  of  sugar  to  4  parts  of  fruit,  and  then 
canning  and  sterilizing.  Tests  conducted  by  the  authors  show  that 
this  product  is  well  adapted  to  use  in  ice  cream. 

Preparation  of  the  Fruit. — In  some  experiments  the  canned  fruits 
of  pie  grade  were  merely  ground  and  added  to  the  mix;  in  others, 
they  were  cooked  with  sugar  after  grinding.  Apricots,  pears,  and  figs 
were  found  to  be  satisfactory  if  added  without  cooking  with  sugar, 
and  treated  as  directed  below.  The  ground  peaches  and  crushed  pine- 
apple were  improved  by  cooking  6  pounds  (one  No.  10  can)  of  the 
fruit  with  2  pounds  of  sugar  for  five  to  ten  minutes.  This  also  pre- 
vented complete  freezing  of  the  pieces  of  fruit.  The  other  fruits  were 
so  finely  ground,  or  rubbed  through  a  sieve,  that  there  were  no  large 
pieces  of  fruit  to  become  icy  in  the  cream. 


Fig.  3 


-Forty-quart  freezer  and  other  equipment  used  in  these  experiments; 
Dairy  Industry  Division,  University  of  California,  at  Davis. 


Directions  for  the  use  of  Various  Canned  Fruits. 

(a)  Apricots:  Grind  or  rub  through  a  sieve  the  contents  of  one 
No.  10  can  of  pie  grade  apricots.  Add  to  45  pounds  of  unflavored  ice 
cream  mix  and  freeze  in  the  usual  manner  to  about  100  per  cent  yield, 
that  is  lP/o  gallons. 

( b )  Figs :  For  a  cream  of  mild  fig  flavor,  grind  the  contents  of  one 
No.  10  can  of  solid  pack  pie  grade  Calimyrna  figs  and  add  to  45 


BUL.  434]  THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES  17 

pounds  of  unflavored  mix.  For  a  " health"  cream  of  very  rich  fig 
flavor,  use  10  pounds  (about  one  and  two-thirds  No.  10  cans)  of  the 
ground  figs  to  45  pounds  of  mix.  Freeze  to  about  100  per  cent  yield, 
that  is,  about  13  gallons. 

(c)  Peaches:  Grind  the  contents  of  two  No.  10  cans  of  pie  grade 
peaches  and  add  4  pounds  of  sugar.  Boil  gently  five  minutes  and  cool. 
Add  about  11  pounds  of  the  prepared  fruit  to  45  pounds  of  ice  cream 
mix  flavored  with  about  one-third  the  amount  of  vanilla  flavoring 
used  for  vanilla  ice  cream.  The  addition  of  a  small  amount  of  peach 
flavor  may  be  required.  Freeze  to  about  100  per  cent  yield,  that  is, 
12  gallons. 

(d)  Pears :  Proceed  as  with  apricots  but  use  11  pounds  of  the 
finely  ground,  solid  pack,  pie  grade  pears  with  45  pounds  of  unflavored 
ice  cream  mix.  A  small  amount  of  yellow  color  may  be  desirable.  If 
canned  crushed  pears  described  on  page  16  are  obtainable,  use  11 
pounds  with  45  pounds  of  mix,  without  grinding  or  cooking. 

(e)  Crushed  Pineapple :  To  the  contents  of  one  case  of  No.  10  cans 
of  crushed  pineapple,  add  35  pounds  of  sugar.  Boil  three  minutes. 
Cool  and  use  V2  gallon  of  the  cooked  fruit  with  45  pounds  of  ice  cream 
mix.6 


INVESTIGATIONS   ON    THE    USE    OF    FRUIT   PRESERVES 
IN   ICE   CREAM 

Fruit  preserves  specially  prepared  for  the  ice  cream  trade  as  well 
as  those  prepared  commercially  for  the  table  were  used  experimentally 
in  ice  cream.  The  principal  objections  to  most  of  such  preparations 
are  their  high  cost  and  high  sugar  content.  Pie  grade  canned  figs, 
apricots,  pears,  and  peaches  are  much  lower  priced  than  the  corre- 
sponding fruit  preserves  and  more  suitable  for  use  in  ice  cream. 
When  sufficient  of  the  ground  fruit  preserves  was  used  to  impart  to 
the  ice  cream  the  characteristic  fruit  flavor  and  appearance,  the  high 
sugar  content  of  the  fruit  so  depressed  the  freezing  point  that  a  too 
soft  ice  cream  was  obtained. 

Berry  preserves  were  open  to  the  same  objections  and  were  found 
to  be  considerably  less  desirable  than  the  cold-p.ack  (frozen)  berries 
for  use  in  ice  cream. 

For  these  reasons,  the  cold-pack  and  commercially  canned  fruits 
are  to  be  preferred  to  the  fruit  preserves. 


6  This  is  the  formula  in  use  in  Hage 's  ice  cream  factory  of  San  Diego  and 
in  the  Dairy  Industry  Division,  Davis,  California. 


18  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 


INVESTIGATIONS  ON  THE   USE  OF   FRUIT  JAMS  IN   ICE  CREAM 

Fruit  jams  for  the  table  are  usually  made  by  cooking  together  about 
equal  weights  of  crushed  fruit  and  sugar,  and  usually  contain  more 
than  50  per  cent  sugar  when  cooked.  A  number  of  fruit  jams  were 
tried  in  ice  cream  but  the  objections  of  high  cost  and  high  sugar  con- 
tent found  with  preserves  applied  with  nearly  equal  force  to  jams. 
While  they  can  be  used,  they  are  much  less  satisfactory  and  are  more 
costly  than  the  corresponding  pie  grade  canned  fruits  and  cold-pack 
fruits. 


INVESTIGATIONS    ON    THE    PREPARATION    AND    USE    OF 
MARASCHINO  CHERRIES   IN   ICE  CREAM 

Cherry  ice  cream  made  with  cherries  prepared  by  the  maraschino 
process  is  of  considerable  commercial  importance,  and  most  factories 
have  found  satisfactory  methods  of  making  cherry  ice  cream.  There 
is,  however,  a  considerable  demand  from  ice  cream  makers  for  infor- 
mation on  methods  of  preparing  the  maraschino  cherries  from  the 
fresh  fruit.  Most  ice  cream  factories  possess  the  equipment  necessary, 
the  principal  requirements  being  a  steam-jacketed  kettle  or  other 
means  of  boiling  several  gallons  of  syrup  and  fruit. 

Numerous  experiments  have  been  conducted  in  the  Fruit  Products 
and  Dairy  Industry  Laboratories  on  the  various  steps  of  the  mara- 
schino process.  The  more  important  of  these  experiments  have  been 
reported  by  A.  II.  Nouty  in  a  recent  Master's  Thesis  in  Fruit 
Products.  Since  these  experiments  are  of  more  interest  to  canners 
and  preservers  than  to  ice  cream  makers,  they  will  be  published  else- 
where and  only  the  working  directions  based  on  them  will  be  given 
here. 

There  are  several  important  steps  in  the  process.  The  first  of  these 
is  storage  of  the  fresh  cherries  in  dilute  sulphurous  acid  solution  to 
harden  the  tissues  and  bleach  the  color.  The  cherries  are  then 
stemmed,  pitted,  and  boiled  in  several  changes  of  water  to  remove 
the  sulphurous  acid  and  to  soften  the  texture  of  the  fruit.  They  are 
then  boiled  and  stored  for  short  periods  in  artificially  colored  and 
flavored  syrups  of  progressively  increasing  sugar  concentration. 

Preparation  of  Maraschino  Cherries. — The  following  procedure  has 
given  good  results  (after  J.  H.  Irish)  : 

(a)  Storage  in  sulphurous  acid  brine:  Place  firm-ripe  Royal  Anne 
cherries  in  a  barrel  or  keg.    Prepare  the  following  solution : 


BUL.  434]  THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES  19 

Water  23  gallons 

Sulphurous  acid  solution  (strength  6%)  2  gallons 

Salt  10  pounds 

Fill  the  container  with  this  solution;  seal  and  store  in  a  cool  room, 
preferably  below  60°  F. 

(6)  First  boiling:  After  a  storage  of  4  weeks  or  longer,  open  the 
barrel  or  keg  and  discard  the  solution.  Stem  and  pit  the  cherries. 
Place  them  in  a  kettle  and  cover  with  water.  Boil  5  minutes  and 
discard  the  water.  Boil  with  three  to  four  additional  lots  of  water 
for  periods  of  about  5  minutes  each;  that  is,  until  the  cherries  are 
tender  and  are  practically  free  from  all  "sulphur"  taste. 

(c)  Syrup  treatment:  Prepare  a  syrup  of  the  following  com- 
position : 

Water  5  gallons 

Sugar 15  pounds 

Citric  acid  crystals  5  ounces 

Certified  red  color,  preferably  Ponceau  3-E  and 
Amaranth  mixed,  to  give  the  desired  tint. 

Boil  the  cherries  in  this  solution  for  3  to  4  minutes.  Set  aside 
overnight.  Then  drain  off  the  syrup  and  test  it  with  a  Baume  or  a 
Balling  hydrometer  and  add  the  dissolved  sugar  to  make  the  syrup  to 
35°  Balling  or  18°  Baume;  or  if  a  hydrometer  is  not  at  hand,  add  to 
each  5  gallons  of  syrup  about  25  pounds  of  sugar.  (The  use  of  a 
hydrometer  is  strongly  urged;  uniform  results  cannot  be  obtained 
without  one.) 

Boil  the  fruit  and  syrup  3  to  4  minutes  and  set  aside  overnight. 

Repeat  the  previous  day's  operations,  bringing  the  syrup  to  40° 
Balling  or  to  21°  Baume  by  adding  sugar,  or  merely  add  another  6 
pounds  of  sugar  to  5  gallons  of  syrup.  If  needed,  also  add  red  color- 
ing. Add  cherry  flavoring  to  suit  or  a  few  drops  of  bitter  almond  oil 
and  proceed  with  step  d. 

(d)  Sterilization:  Heat  syrup  and  fruit  to  boiling.  Pack  into 
glass  fruit  jars  fitted  with  rubbers  and  glass  tops.  Seal  loosely.  Place 
in  a  steam  box  or  in  a  bath  of  hot  water  and  heat  in  live  steam  or  in 
boiling  water  for  20  minutes.    Remove  and  seal  tightly. 

A  simpler  method  of  preservation  is  as  follows :  Heat  cherries  and 
syrup  to  boiling.  Set  aside  overnight.  Place  in  wooden  kegs  or  in 
heavily  paraffined  ice  cream  cans  and  store  in  the  hardening  room  at 
zero  to  15°  F. 

Using  the  Maraschino  Cherries  in  Ice  Cream. — Grind  the  cherries 
and  add  2%  pounds  to  45  pounds  of  unflavored  mix.  Add  color  and 
flavor  to  suit. 


20  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 


INVESTIGATIONS    ON    THE    USE    OF    FRUIT   JUICES,    SYRUPS,    AND 
CONCENTRATES    IN    ICE    CREAM 

Orange  juice  is  the  only  fruit  juice  that  is  very  well  suited  to  use 
in  ice  cream.  Although  grape,  berry,  and  other  fruit  juices  and  also 
syrups  and  concentrates  made  from  them,  were  used  in  ice  cream  with 
fair  success,  they  were  much  more  satisfactory  in  water  ices  and  will 
be  discussed  in  that  connection.     See  page  25. 

The  preparation  of  ice  cream  with  fresh  orange  juice  is  described 
on  page  8.  Orange  syrup  made  with  sugar  can  be  substituted  for  the 
juice,  if  it  is  first  diluted  with  three  times  its  volume  of  water  and 
if  the  same  volume  of  the  diluted  syrup  is  used  as  is  recommended 
for  juice,  page  8.    No  additional  sugar  is  needed. 

Orange  concentrates  (orange  juice  slightly  sweetened  and  con- 
centrated in  vacuo  to  a  thick  consistency)  of  good  quality  are  now 
obtainable  and  may  be  used  to  replace  most  of  the  fresh  juice  in  any 
good,  orange  ice  cream  formula.  However,  the  use  of  some  fresh 
orange  juice  is  highly  desirable  in  order  to  furnish  the  fresh  fruit 
flavor  which  the  concentrate  lacks.  The  following  formula  has  given 
satisfactory  results : 

Orange  concentrate  1  pound 

Water  5  pounds 

Fresh  orange  juice 1  pound 

Add  to  45  pounds  of  ice  cream  mix  and  add  color  and  orange  oil 
to  suit.  One  pound  of  concentrate  is  equivalent  to  about  six  pounds 
of  fresh  juice. 


INVESTIGATIONS  ON  THE  USE  OF  CANDIED  FRUITS  IN  ICE  CREAM 

Considerable  quantities  of  candied  fruits  are  used  in  special  ice 
cream  such  as  tutti-frutti  and  in  frozen  puddings.  The  broken,  ground 
or  chopped  candied  fruits,  representing  wholesome  fruit  unsuitable 
for  packing  for  the  candy  trade,  can  be  purchased  at  moderate  cost 
from  candied  fruit  factories  or  ice  cream  supply  houses.  These 
products  are  satisfactory  for  the  purpose  intended.  As  the  process 
of  preparing  candied  fruits  is  troublesome  and  costly,  and  as  the 
average  ice  cream  factory  uses  only  relatively  small  quantities,  there 
is  no  need  for  the  ice  cream  manufacturer  to  make  candied  fruits. 
The  process  is  not  difficult,  but  requires  about  three  weeks  or  longer.7 

7  Directions  for  making  fruit  candy  may  be  found  in:  Cruess,  W.  V.  and 
Agnes  O'Neill.  The  home  preparation  of  fruit  candy.  California.  Agr.  Ext. 
Service  Cir.  10:1-28.     1927. 


BUL.  434]  THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES  21 

The  larger  pieces  of  candied  fruits,  such  as  candied  figs  or  apricots 
cut  in  half  or  candied  peaches  or  pears  cut  in  quarters,  may  be  used 
in  aufait  creams;  that  is,  they  may  be  placed  between  layers  of 
different  kinds  of  cream  for  the  making  of  bricks.  When  used  in 
this  manner,  they  add  greatly  to  the  appearance  of  the  cream. 


INVESTIGATIONS   ON    THE    USE   OF    DRIED    FRUITS    IN    ICE    CREAM 

A  number  of  different  dried  fruits  were  prepared  in  various  ways 
and  used  experimentally  in  ice  cream.  Of  these,  prunes  and  raisins 
appear  to  have  the  greatest  commercial  possibilities.  While  dried 
apricots,  peaches,  and  figs  can  be  used  in  ice  cream,  the  canned  and 
cold-pack  fruits  of  these  varieties  are  much  better  for  the  purpose  and 
much  more  convenient  to  use.  For  these  reasons  most  attention  will 
be  given  to  prunes  and  raisins  in  the  following  discussion. 

Prunes. — Prunes  are  used  in  the  diet  largely  on  account  of  their 
well  known  physiological  effect.  They  are  of  particular  value  as  a 
food  for  children  and  convalescents.  Unfortunately,  however,  many 
people,  especially  some  in  the  two  classes  of  consumers  mentioned 
above,  are  not  fond  of  prunes  and  if  they  eat  them  at  all,  do  so  largely 
as  a  matter  of  duty. 

Experiments  with  prune  ice  cream  resulted  in  a  product  possessing 
a  very  attractive  appearance  and  pleasing  flavor.  It  is  believed  that 
prunes  in  this  form  will  appeal  to  any  one  who  likes  ice  cream,  and 
that  prune  ice  cream  will  be  especially  desirable  for  use  as  a  food  for 
children  and  for  convalescents  whether  in  hospitals,  sanitariums,  or 
in  the  home. 

Ice  cream  was  made  with  prunes  prepared  in  the  following  ways: 

(a)  With  canned  prune  pulp  :8  The  most  satisfactory  of  the 
methods  tested  of  preparing  prunes  for  the  ice  cream  trade  was  found 
to  be  as  follows :  The  dried  prunes  were  boiled  in  water  until  soft  and 
were  then  passed  through  a  medium-coarse  screen  in  a  tomato  pulper, 
which  separated  the  pulp  from  the  pits.  The  resulting  pulp  was  heated 
almost  to  boiling,  canned,  and  sealed  hot,  and  then  sterilized  in  boiling 
water.  The  product  thus  prepared  contained  about  60  per  cent  of 
water.  It  can  be  prepared  at  small  cost  by  any  fruit  cannery,  and  if 
a  demand  is  created  for  it  arrangements  can  be  made  to  have  it 
prepared  for  the  ice  cream  trade. 


s  This  process  of  preparing  prunes  was  developed  by  E.  Mrak,  a  graduate 
research  assistant  in  Fruit  Products. 


22  UNIVERSITY  OF   CALIFORNIA — EXPERIMENT  STATION 

An  ice  cream  for  the  soda  fountain  trade  and  for  dessert  purposes 
is  made  by  using  20  per  cent  by  weight  of  this  pulp  with  45  pounds 
of  unflavored  ice  cream  mix.  This  corresponds  to  about  11  pounds  to 
45  pounds  of  mix.  Freeze  to  about  12  gallons.  For  a  health  cream, 
a  mix  containing  about  30  per  cent  of  prune  pulp  was  satisfactory; 
this  corresponds  to  the  addition  of  pulp  in  the  ratio  of  20  pounds  to 
45  pounds  of  mix,  or  10  pounds  to  22%  pounds  of  mix.  The  basic 
mix  must  contain  in  this  case  about  12  per  cent  of  fat  in  order  that 
the  finished  cream  will  contain  more  than  the  legal  minimum  of  8 
per  cent. 

The  "health"  cream  is  best  served  fresh,  as  it  tends  to  become 
somewhat  rough  in  texture  on  prolonged  storage  in  the  hardening 
room.  With  the  lower  proportion  of  prune  pulp,  the  ice  cream 
retains  its  texture  very  well  in  the  hardening  room. 

(b)  With  cooked  prunes:  While  considerable  trouble  and  time  are 
involved,  it  is  possible  for  the  ice  cream  maker  to  prepare  prune  pulp 
from  the  dried  fruit.  A  number  of  methods  of  cooking  the  prunes 
were  compared  and  the  most  satisfactory  was  found  to  be  about  as 
follows  : 

To  7  pounds  of  dried  prunes  add  4  quarts  of  water.  Bring  to 
boiling  and  set  aside  overnight.  Then  boil  gently  until  soft;  usually 
20  minutes  will  be  sufficient.  Discard  the  water  in  which  the  prunes 
were  cooked.  Rub  the  fruit  through  a  colander  or  coarse  screen  to 
remove  pits  or  pit  by  hand  and  grind  in  a  food  chopper.  Use  as 
directed  in  (a)  for  canned  prune  pulp. 

No  sugar  should  be  added  to  prunes  cooked  for  use  in  ice  cream. 

(c)  With  pitted  prunes:  Small  pitted  prunes  were  used  in  some 
tests.  These  may  be  purchased  from  packers  of  dried  prunes.  They 
were  cooked  with  about  1%  volumes  of  water,  ground,  and  used  as 
previously  described  for  pulp  and  cooked  prunes.  Unfortunately, 
these  prunes  carry  a  considerable  number  of  pieces  of  broken  pits  and 
for  this  reason  are  of  doubtful  value  for  use  in  ice  cream. 

(d)  With  canned  ready-to-serve  prunes:  Prunes  canned  in  light 
syrup  in  No.  10  cans  are  obtainable  but  are  of  course  more  costly  than 
the  plain  dried  prunes.  Canned  prunes  used  in  ice  cream  were  satis- 
factory. They  were  rubbed  through  a  screen  to  remove  pits,  and  the 
pulp  was  mixed  with  the  syrup  before  adding  to  the  ice  cream  mix. 

Raisins. — Raisins  have  been  used  in  ice  cream  to  a  considerable 
extent  in  the  eastern  states.  Usually,  however,  the  mistake  has  been 
made  of  using  Thompson  seedless  instead  of  Muscat  raisins.     The 


BUL.  434]  THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES  23 

Thompson  seedless  is  poorly  adapted  for  this  purpose  because  it  is 
almost  wholly  lacking  in  flavor.  On  the  other  hand,  Muscat  raisins 
possess  a  very  pronounced  flavor  that  is  pleasing  and  may  be  readily 
recognized  in  the  ice  cream.  A  mixture  of  Muscat  and  Thompson 
seedless  raisins  is  fairly  satisfactory.  A  number  of  experiments  were 
made  to  determine  the  most  satisfactory  method  of  preparing  the 
raisins  for  use  in  ice  cream  and  to  determine  the  proper  amount  to  be 
added  to  the  mix. 

(a)  With  bulk  raisins:  Seeded  bulk  Muscat  raisins  of  bakers' 
quality  and  bulk  Thompson  seedless  raisins  were  used  in  the  experi- 
ments. The  raisins  were  soaked  and  cooked  with  various  proportions 
of  water ;  some  were  ground  before  use,  others  were  used  whole,  and 
various  amounts  of  the  different  preparations  were  added  to  basic  ice 
cream  mix.  As  stated  above,  the  Thompson  seedless  raisins  used  alone 
proved  unsatisfactory  because  of  lack  of  distinctive  flavor.  Less  than 
10  per  cent  of  Muscat  raisins  gave  an  ice  cream  of  weak  flavor;  the 
best  proportion  was  found  to  be  about  15  per  cent  by  weight;  that 
is,  about  8  pounds  of  the  prepared  raisins  to  45  pounds  of  mix. 

When  whole  raisins  only  were  added,  the  appearance  was  not  so 
satisfactory  and  the  flavor  was  less  pronounced  than  when  about  half 
of  the  raisins  were  ground  and  the  remainder  added  whole.  A  satis- 
factory combination  was  equal  weights  of  ground  Muscat  raisins  and 
whole  Thompson  seedless  raisins. 

When  more  than  40  per  cent  of  water,  i.e.,  4  pounds  of  water  to 
6  pounds  of  raisins,  was  used,  the  ice  cream  was  pale  in  color  and  too 
watery,  giving  a  rough  cream.  From  20  to  30  per  cent  added  water 
was  found  best.  When  no  water  was  added,  the  raisins  were  tough 
after  the  cream  was  frozen ;  also  they  tended  to  sink  toward  the  bottom 
of  the  ice  cream  cans  or  brick  pans  unless  the  cream  was  unusually 
stiff  when  drawn. 

Based  on  these  findings,  the  following  alternative  procedures  are 
recommended : 

(1)  To  5  pounds  of  Muscat  raisins  add  3  pints,  or  3  pounds,  of 
water.  Mix  well.  Warm  gently  to  nearly  the  simmering  point,  that 
is,  to  about  165°  F,  but  do  not  allow  to  boil.  Set  aside  about  two 
hours;  stir  occasionally  during  this  period  to  facilitate  absorption  of 
the  water.  Grind  one-half  of  the  raisins.  Mix  with  the  unground 
raisins  and  the  syrup.  Add  to  the  45  pounds  of  unflavored  ice  cream 
mix  and  freeze  to  100  per  cent  yield,  or  about  11%  gallons. 


24  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

(2)  To  2%  pounds  of  Muscat  raisins,  add  iy2  pounds  of  water; 
heat,  soak,  and  grind  all  of  the  raisins  as  directed  above.  Prepare 
2y2  pounds  of  Thompson  seedless  in  similar  manner  but  do  not  grind. 
Mix  the  ground  Muscats,  whole  Thompson  seedless,  and  the  syrup. 
Add  to  45  pounds  of  mix.    Freeze  to  about  11%  gallons. 

(6)  With  commercially  canned  raisins:  Some  seeded  Muscat  raisins 
are  canned  commercially  and  are  practically  ready  to  use  in  ice  cream. 
If  4  pounds  of  the  canned  raisins  are  ground,  mixed  with  4  pounds  of 
the  whole  canned  raisins  and  added  to  45  pounds  of  mix,  an  excellent 
raisin  ice  cream  is  obtained. 

(c)  Canning  raisins  for  the  ice  cream  trade :  Numerous  raisin 
preparations  were  canned  and  used  experimentally  in  ice  cream.  The 
best  method  consisted  in  mixing  equal  quantities  of  ground  and  whole 
raisins  prepared  as  described  in  (a),  heating  to  about  160°  F,  canning 
and  sealing  hot,  and  then  sterilizing  in  boiling  water  45  minutes  for 
small  cans  and  60  minutes  for  No.  10  cans.  These  raisins  are  ready  to 
use,  one  No.  10  can  being  sufficient  for  45  pounds  of  mix. 

Dried  Figs. — Dried  figs  are  much  less  satisfactory  than  the  fresh 
or  the  canned  and  are  not  recommended  unless  the  former  cannot  be 
obtained.  Black  Mission,  White  Adriatic,  Calimyrna,  and  Kadota 
dried  figs  were  compared  in  respect  to  their  suitability  for  use  in  ice 
cream.  Of  these,  the  Calimyrna  proved  best,  with  the  Mission  second. 
Neither  of  the  other  two  varieties  was  entirely  satisfactory.  The 
addition  of  sugar  in  cooking  was  found  desirable  in  order  to  prevent 
freezing  of  the  fig  meat  to  an  icy  texture  in  the  ice  cream. 

Of  the  various  methods  of  preparing  the  figs  tested  the  following 
proved  best:  To  2  pounds  of  dried  figs,  add  3  quarts  of  water.  Soak 
overnight.  Add  l1/^  pounds  of  sugar.  Cook  slowly  until  tender — 
about  1  to  IV2  hours.  Weigh,  and  if  the  weight  is  less  than  6  pounds, 
add  water  to  make  the  weight.  If  it  is  more  than  6  pounds,  boil  off 
excess  water  until  a  weight  of  about  6  pounds  is  attained.  Cool  and 
then  grind.  Add  to  45  pounds  of  ice  cream  mix;  the  addition  of  a 
small  amount  of  vanilla  is  usually  desirable.  Freeze  to  about  11 
gallons. 

The  cooked  whole  figs  and  those  cut  in  half,  particularly  Missions, 
are  suitable  for  use  in  aufait. 

Dried  Apricots. — These  are  not  nearly  so  satisfactory  as  the  fresh 
or  the  canned.  They  may,  however,  be  prepared  and  used  as  described 
for  dried  figs,  except  that  1%  pounds  of  fruit,  1  pound  of  sugar,  and 
3  quarts  of  water  are  used.     Bring  final  cooked  weight  to  6  pounds. 

Other  Dried  Fruits. — Dried  pears,  peaches,  and  apples  are  not 
recommended  for  use  in  ice  cream. 


BUL.  434]  THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES  25 


INVESTIGATIONS  ON  THE   USE  OF  FRESH   FRUITS   IN  WATER   ICES 

Water  ices  differ  from  sherbets  in  one  respect :  some  ice  cream  mix 
or  other  form  of  milk  solids  is  added  to  sherbets  but  none  to  water 
ices.  Both  consist  essentially  of  fruit  juice,  sugar,  water,  and  stabiliz- 
ing colloid  frozen  to  the  consistency  of  ice  cream.  The  water  ices  will 
be  considered  first  as  they  are  more  important  than  the  sherbets. 

There  is  a  large  potential  market  for  fruit  ices,  undeveloped  prin- 
cipally because  in  the  past  fruit  ices  have  been  "poor  keepers,"  often, 
if  not  usually,  becoming  rough  in  texture  and  "bleeding"  before  they 
have  been  dispensed.  These  defects  are  usually  inherent  in  the  basic 
water  ice  mixes  used  commercially. 

Fruit  ices  are  the  ideal  frozen  dessert  for  summer  months  because 
they  are  acid  in  flavor  and  thus  thirst  quenching  and  refreshing. 
They  deserve  greater  popularity  than  at  present  exists. 

One  very  important  cause  for  their  relatively  slight  popularity  is 
that  mentioned  in  the  introduction  to  this  bulletin.  In  general,  too 
small  a  proportion  of  fruit  is  used  in  so-called  fruit  ices,  a  fault  which 
some  ice  cream  manufacturer  attempts  to  remedy  by  the  addition  of 
excessive  amounts  of  color  and  flavor. 

Comparison  of  Various  Basic  Water  Ice  Mixes. — In  the  earlier 
experiments,  a  basic  mix  containing  gelatin  as  the  colloid  for  stabiliz- 
ing the  ice  was  used.    This  mix  consisted  of : 

Water  15  quarts 

Lemon  juice,  fresh 24  ounces 

Sugar To  give  28  per  cent  solids 

Gelatin 0.7  per  cent 

Except  with  orange  and  lemon  juices,  the  gelatin  reacted  with  the 
coloring  matter  and  tannin  of  the  fruit  juice  to  give  a  grayish  pre- 
cipitate, which  injured  the  appearance  of  the  ice.  All  ices  made  with 
gelatin  were  short  lived.  They  soon  became  rough  in  texture  and 
bled;  that  is,  the  juice  or  syrup  tended  to  separate  from  the  ice 
crystals,  giving  a  mass  of  ice  in  the  top  of  the  container  and  a  syrup 
at  the  bottom. 

Because  the  basic  mix  containing  gelatin  proved  so  unsatisfactory 
with  fruit  juices,  various  mixes  developed  in  the  investigation  pre- 
viously mentioned  (see  footnote,  page  5)  were  tried,  for  the  prepara- 
tion of  both  small  experimental  and  commercial  lots  of  water  ices. 
One  new  basic  mix  proved  successful  for  use  with  juices.  None  of 
these  colloids  forms  precipitates  with  constituents  of  the  fruit  juices. 


26  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

Furthermore,  they  give  ices  of  remarkably  long  life,  the  ices  having 
been  kept  in  the  hardening  room  for  a  month  without  appreciable 
"roughening"  of  the  texture  and  "bleeding."  Another  very  desir- 
able characteristic  is  their  freedom  from  disagreeable  taste,  if  products 
of  good  quality  are  used.  Many  gelatins  impart  a  disagreeable  flavor 
to  the  ice  or  mask  the  fruit  flavor. 

It  was  found  in  other  experiments  that  the  acidity  of  the  water 
ice  greatly  affected  the  texture  and  other  qualities  as  well  as  the  flavor, 
and  that  the  best  results  were  obtained  with  an  acidity  equivalent  to 
0.6  to  0.65  grams  of  acid  (as  citric)  per  100  cc. 

The  investigations  on  the  effect  of  composition  of  the  basic  mix  on 
the  quality  of  water  ices  were  not  an  integral  part  of  the  investigations 
given  in  this  bulletin.  However,  in  applying  the  major  results  of  the 
water  ice  investigations  to  actual  practice,  the  following  basic  mix 
was  found  very  satisfactory : 

Cane  sugar 21  pounds 

Pure  corn  sugar  crystals 7  pounds9 

Agar  agar,  highest  grade  powdered 0.15  pounds  (2y2  ounces) 

Gum  tragacanth,  powdered 0.35  pounds  (5^  ounces) 

Make  to  80  pounds  with  water,  and  add  sufficient  citric  acid  to 
give,  when  mixed  with  fruit  or  fruit  juice,  a  final  acidity  of  0.6  per 
cent  as  citric.  Ordinarily,  this  may  be  taken  as  about  6  to  8  ounces  of 
citric  acid  to  100  pounds  of  mix  after  addition  of  fruit. 

Proportion  of  Fruit. — In  most  cases  20  per  cent  by  weight  of  fruit 
or  fruit  juice  was  used.  Sometimes  it  may  be  necessary  to  use  a 
greater  proportion  than  this,  where  the  flavor  of  the  fruit  is  not  very 
pronounced.  If  more  than  20  per  cent  fruit  is  used,  due  allowance 
should  be  made  in  the  basic  mix  by  adding  more  colloids,  i.e.,  agar  agar 
and  gum  tragacanth,  etc. 

Fresh  Apricot  Ice. — As  in  ice  cream,  the  cooked  fresh  apricots  were 
found  superior  to  the  raw  fruit  for  use  in  water  ice.  The  following 
formula  is  based  on  this  finding : 

To  10  pounds  of  pitted,  ground,  thoroughly  ripe  apricots,  add 
2V2  pounds  of  sugar.  Boil  three  to  five  minutes  and  cool.  Add  9 
pounds  to  sufficient  basic  water  ice  mix  to  give  5  gallons.  Freeze  to  not 
more  than  35  per  cent  yield. 

The  basic  mix  in  this  case  should  be  made  with  about  6  ounces  of 
citric  acid  added  to  each  100  pounds  of  mix,  or  with  lemon  juice  to 
give  the  desired  acidity. 

0  Cerelose,  pure  commercial  corn  sugar,  was  used. 


BlJL.  434]  THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES  27 

Fresh  Berry  Ices. — Fresh  berries  are  very  satisfactory  for  use  in 
water  ices,  strawberry  ice  being  the  most  popular.  Of  the  other 
common  berries,  loganberries  and  raspberries  are  probably  best.  Cran- 
berry water  ice  is  very  popular  during  the  holiday  season. 

Uncooked  berries  proved  best  for  use  in  water  ice.  Cranberries 
were  an  exception,  however,  and  were  not  at  all  satisfactory  unless 
cooked  before  freezing. 

Various  proportions  of  berries  and  basic  mix  were  tried  with  the 
conclusion  that  an  addition  of  about  20  per  cent  of  the  prepared  fruit 
to  the  basic  mix  gave  the  best  results.  More  fruit  than  this  made  the 
ice  too  pulpy  or  jam-like ;  very  much  less  made  the  flavor  and  color  too 
dilute.  The  formulas  given  below  are  based  on  trials  in  the  laboratory 
and  on  experience  of  the  Dairy  Industry  Division  in  preparing  water 
ices  commercially. 

(a)  Blackberry,  loganberry,  raspberry,  and  strawberry  ices:  To 
10  pounds  of  hulled,  washed,  crushed  berries,  add  3  pounds  of  cane 
sugar.  Stir  until  dissolved.  Add  9  pounds  to  basic  water  ice  mix  to 
give  5  gallons  and  citric  acid  to  increase  total  acidity  to  0.6  per  cent; 
or,  preferably,  use  a  basic  mix  containing  about  6  ounces  of  citric 
acid  in  100  pounds  of  mix.    Freeze  to  about  35  per  cent  yield. 

See  page  26  for  formula  for  basic  mix. 

(b)  Cranberry  ice:  Cranberries,  it  was  found,  give  a  rather  bitter 
ice  unless  first  blanched  in  boiling  water.  This  is  taken  into  account 
in  the  following  formula: 

To  9  pounds  of  cranberries,  add  l1/^  gallons  of  boiling  water ;  allow 
to  stand  two  minutes,  then  discard  the  wTater.  Again  add  1  gallon  of 
water  and  2%  pounds  of  sugar.  Boil  until  the  berries  are  soft.  Rub 
through  a  colander  or  screen  and  add  9  pounds  to  basic  water  ice  mix 
to  give  5  gallons.    Freeze  to  about  35  per  cent  yield. 

Fresh  Grape  Ice. — In  season,  fresh  grapes  can  be  used  to  good 
advantage  in  water  ice.  Juice  from  thoroughly  ripe  Muscat  grapes 
gave  a  very  good  water  ice  and  a  mixture  of  the  Muscat  and  any  red 
grape  juice  was  also  satisfactory.  The  eastern  varieties  such  as  Pierce 
Isabella  and  Concord  were  found  superior  to  most  California  (Vini- 
fera)  varieties,  for  water  ices. 

To  extract  the  juice  from  Muscat  grapes,  crush  thoroughly  and 
express  the  juice  in  a  fruit  juice  press  or  by  applying  pressure  to  the 
crushed  grapes  in  a  sugar  bag.  The  juice  should  be  strained  through 
cheesecloth  or  a  sugar  bag  to  remove  coarse  particles,  but  need  not 
be  perfectly  clear. 


28 


UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 


To  extract  the  juice  from  red  juice  grapes,  such  as  Pierce  Isabella, 
Alicante  Bouschet,  and  Zinfandel,  crush  thoroughly;  heat  to  about 
160°  F  and  press  or  squeeze  the  juice  through  a  bag. 

Add  no  sugar.  To  4%  to  5  quarts  of  the  juice,  add  basic  water  ice 
mix  to  give  5  gallons.  The  basic  mix  should  be  prepared  to  contain 
about  6  ounces  of  citric  acid  per  100  pounds  of  mix.  Freeze  to  not 
more  than  35  per  cent  yield. 


Revolving  cone  citrus  juice  extractor. 


Fresh  Lemon  Ice. — Of  the  various  proportions  of  lemon  juice 
tested,  about  iy2  per  cent  gave  the  best  results.  The  juice  expressed 
on  a  revolving  cone  was  found  to  be  of  better  flavor  for  use  in  water 
ice  than  that  expressed  by  pressing  the  whole  fruit.  The  following 
formula  has  proved  satisfactory. 

Cut  the  lemons  in  half  and  express  the  juice.  Strain  out  the  seeds 
and  coarse  pieces  of  "rag. "  To  3  pints  of  the  juice,  add  3  pounds  of 
sugar  and  3  pints  of  water  with  basic  mix  to  give  5  gallons.  If  the 
flavor  is  too  faint,  add  a  few  drops  of  best  quality  lemon  oil  or  extract. 
A  small  amount  of  lemon  yellow  color  improves  the  appearance.    The 


BUL.  434]  THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES  29 

basic  mix  in  this  case  should  be  made  with  about  4  ounces  of  citric  acid 
in  100  pounds  of  mix.  Lemon  juice  usually  contains  about  6  per  cent 
citric  acid.    Freeze  to  not  more  than  35  per  cent  yield. 

Fresh  Orange  Ice. — Orange  ice  made  with  the  fresh  juice  is  much 
superior  in  flavor  to  that  made  with  syrups  or  concentrates.  Most 
factories  now  use  too  little  juice  and  altogether  too  much  artificial 
color  and  flavor  in  their  orange  ice.  About  4%  quarts  of  fresh  juice 
with  basic  mix  to  give  5  gallons  should  be  used.  Where  obtainable, 
cull  oranges  or  *  'juice  grade"  oranges  may  be  utilized.  They  are 
equally  as  good  as  the  higher  priced  oranges  for  orange  ice.  The 
Valencia  gave  ices  of  slightly  better  flavor  than  the  Navel,  but  the 
difference  was  slight.  The  basic  mix  should  contain  about  0.4  per  cent 
acid  before  addition  of  the  orange ;  that  is,  about  6  ounces  of  citric 
acid  in  100  pounds  of  mix. 

To  prepare  the  ice :  Extract  the  juice  from  the  halved  fruit  on  a 
revolving  cone.  Strain  through  a  sieve  or  colander  to  eliminate  seeds 
and  very  coarse  pulp.  To  4%  quarts  of  the  juice,  add  basic  mix  to  give 
5  gallons.  Add  a  small  amount,  not  too  much,  orange  color  if  needed, 
and  a  very  small  amount  of  orange  oil.  Freeze  to  about  35  per  cent 
yield. 

Fresh  Peach  Ice. — The  common  canning  and  drying  varieties  of 
peaches  did  not  prove  satisfactory  in  ice.  .If  highly  flavored,  juicy 
table  peaches  are  obtainable,  peel  and  proceed  as  directed  for  apricot 
ice. 

Fresh  Plum  Ice. — In  experiments  made  at  the  Lincoln  Cannery  by 
one  of  the  authors10  in  1922,  it  was  found  that  highly  colored  varieties 
of  plums  such  as  the  Damson,  Blue  Diamond,  Satsuma,  and  Grand 
Duke  were  satisfactory  for  use  in  water  ices.  As  a  result  of  these 
experiments,  the  following  procedure  is  recommended : 

Use  thoroughly  ripe- plums.  Crush.  To  10  pounds  of  plums,  add 
1  gallon  of  water.  Boil  four  to  five  minutes.  Strain  through  a  sugar 
bag.  To  each  gallon  of  juice,  add  3  pounds  of  sugar.  To  4a/2  quarts 
of  the  sweetened  juice  add  basic  water  ice  mix  to  give  5  gallons. 
Freeze  to  about  35  per  cent  yield.  The  basic  mix  used  should  contain 
about  5  ounces  of  citric  acid  in  100  pounds. 

Fresh  Pomegranate  Ice. — Because  of  the  great  difficulty  in  expres- 
sing the  juice  in  the  average  ice  cream  plant,  it  is  recommended  that 
only  the  bottled  juice  be  used.     See  page  30. 


10  See  Cruess,  W.  V.    Utilization  of  surplus  plums.     California  Agr.  Exp.  Sta. 
Bui.  400:1-21.     1926. 


30  UNIVERSITY  OF   CALIFORNIA — EXPERIMENT  STATION 


INVESTIGATIONS   ON   THE    USE   OF   BOTTLED    FRUIT  JUICES 
IN  WATER   ICES 

Fresh  fruit  juices  are  naturally  better  than  the  juice  preserved  by 
heat  or  other  means,  but  unfortunately  the  season  for  most  fresh 
fruits  is  short  and  for  many  fruits  does  not  correspond  with  the  period 
of  greatest  demand  for  fruit  ices.  Consequently,  it  becomes  necessary 
to  use  the  preserved  juices  to  some  extent. 

Bottled  grape  juice,  loganberry,  and  pomegranate  juices  preserved 
by  pasteurization  are  obtainable.  It  is  most  economical  to  buy  the 
juices  by  the  case  in  gallon  bottles. 

Bottled  loganberry,  grape,  pomegranate,  lemon,  orange,  black- 
berry, strawberry,  and  apple  juices  were  tried.  The  citrus  juices  were 
very  unsatisfactory  because  of  their  pronounced  cooked  flavor;  and 
in  some  cases,  especially  in  samples  more  than  six  months  old,  there 
was  a  very  disagreeable  "stale"  or  "turpentiney"  flavor.  Other 
investigations  have  proved  that  there  is  at  present  no  practicable 
method  of  preserving  fresh  citrus  juices  except  by  freezing  in  storage 
or  by  conversion  into  syrups  or  concentrates. 

Pomegranate,  grape,  loganberry,  and  blackberry  juices  were  satis- 
factory. The  pomegranate  and  berry  juices  were  slightly  sweetened 
with  sugar  before  bottling ;  the  grape  was  not  sweetened.  These  juices 
gave  good  results  when  used  in  the  same  manner  as  the  fresh; 'that 
is,  4V£  quarts  of  juice  were  added  to  sufficient  basic  water  ice  mix 
to  give  5  gallons.  Pomegranate  is  the  least  desirable  because  of  its 
rather  mild  flavor. 

Strawberry  juice  a  few  weeks  after  bottling  was  of  very  poor  color 
and  much  inferior  to  the  fresh  berries  in  flavor.  The  cold-pack  straw- 
berries are  the  only  satisfactory  substitute  for  the  fresh,  all  things 
considered. 

A  satisfactory  ice  was  made  with  apple  juice,  but  compared  with 
fresh  strawberry,  grape,  and  orange  ices  it  was  rather  insipid.  It 
seems  to  have  no  very  great  commercial  possibilities  in  this  state; 
consumers  prefer  to  use  unfermented  cider  as  a  beverage. 


INVESTIGATIONS    ON    THE    USE    OF    FRUIT    CONCENTRATES 
IN  WATER   ICES 

Fruit  concentrates  are  the  natural  fruit  juices  concentrated  to  the 
consistency  of  syrups.  Usually  very  little  or  no  sugar  is  added. 
Facilities  exist  in  several  fruit  products  factories  in  this  state  for  the 
concentration  of  fruit  juices  in  vacuo  in  glass-lined  vacuum  pans,  and 


BUL.  434]  THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES  31 

in  other  factories  by  the  freezing  process.  A  number  of  different 
commercially  and  experimentally  prepared  concentrates  were  tried. 
Of  these,  orange  and  grape  concentrates  were  the  most  satisfactory. 
Concentrates  made  from  various  berries  and  pomegranates  by  vacuum 
concentration  were  very  unsatisfactory  because  they  lacked  flavor  and 
had  poor  color.  In  some  cases,  the  concentration  had  caused  the 
products  to  take  on  a  very  disagreeable,  astringent  taste.  Most  of 
those  concentrated  in  metal  vacuum  pans  possessed  a  metallic  taste. 
A  sweetened  pineapple  concentrate  gave  fair  results. 

Juices  concentrated  by  freezing  possessed  much  more  of  the  fresh 
flavor  of  the  fruit  than  did  those  made  by  vacuum  concentration. 
Lemon  concentrate  was  dark  brown  in  color  and  of  stale  lemon  flavor, 
and  was  wholly  unsuited  to  use  in  water  ice. 

If  the  technique11-  of  preparing  fruit  concentrates  is  improved  so 
that  the  fresh  fruit  flavor  and  color  are  well  retained,  there  should  be 
a  considerable  market  for  such  products  in  the  ice  cream  industry. 

Only  the  orange  and  grape  concentrates  will  be  discussed  further, 
owing  to  the  fact  that  the  other  concentrates  were  either  entirely 
unsatisfactory  or  require  great  improvement  in  the  present  method 
of  manufacture  in  order  to  render  them  very  satisfactory  for  use  in 
water  ices.12 

Orange  Concentrate. — Two  commercially  prepared  bottled  orange 
concentrates  were  tried.  Some  of  each  was  used  when  first  received, 
and  portions  of  each  were  stored  at  room  temperature  and  at  the 
temperature  of  the  ordinary  ice  cream  hardening  room,  zero  to  5°  F. 
The  freshly  prepared  concentrates  and  those  held  at  zero  to  5°  F  even 
for  three  years  were  fairly  satisfactory  for  use  in  water  ice,  provided 
a  small  amount  of  fresh  juice  was  also  used  to  mask  the  cooked  taste 
of  the  concentrate.  The  concentrates  stored  at  room  temperature  soon 
darkened  in  color,  finally  becoming  almost  black,  and  also  acquired  a 
strong  medicinal  or  "stale"  orange  flavor.  It  is,  therefore,  recom- 
mended that,  when  orange  concentrate  is  used,  it  be  purchased  within 
a  few  days  after  manufacture,  and  that  the  concentrates  be  stored  in 
the  hardening  room  or  used  very  soon  after  purchase. 

Numerous  experimental  lots  of  orange  ice  were  prepared  with  the 
concentrate,  different  proportions  of  concentrate  being  used  with  and 
without  the  addition  of  fresh  juice. 


11  For  details  of  various  processes  of  concentrating  fruit  juices  see:  Irish, 
J.  H.    Fruit  juice  concentrates.     California  Agr.  Exp.  Sta.  Bui.  392:1-20.     1925. 

12  The  names  of  manufacturers  of  fruit  concentrates  and  fruit  juices  will  be 
sent  upon  request,  to:  Division  of  Viticulture  and  Fruit  Products,  University  of 
California,  Berkeley. 


32  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

The  following  formula  gave  the  best  results  : 

Orange  concentrate 15  ounces 

Water 4  pints 

Fresh  orange  juice 4  pints 

Orange  oil About  ten  drops 

Basic  mix  to  give  5  gallons  and  orange  color  to  give  the 
desired  color  if  needed. 

The  basic  mix  should  be  prepared  with  about  6  ounces  of  citric 
acid  in  100  pounds  of  mix. 

Grape  Concentrate. — Only  grape  concentrate  of  red  color  was 
found  satisfactory.  The  color  must  be  a  deep  purplish  red,  not  a 
reddish  brown.  The  addition  of  some  fresh  or  bottled  grape  juice  is 
desirable  in  order  to  furnish  flavor.  The  following  formula  can  be 
recommended : 

Grape  concentrate  (red) 1  quart 

Water  3  pints 

Fresh  or  bottled  Concord,  Isabella,  or  Muscat  juice  2  quarts 
Basic  mix  to  give  5  gallons. 

The  basic  mix  should  be  made  with  about  6  ounces  of  citric  acid 
in  100  pounds  of  mix. 

INVESTIGATIONS  ON  THE  USE  OF  FRUIT  SYRUPS  IN  WATER  ICES 

Fruit  syrups  differ  from  fruit  concentrates  in  that  they  are  pre- 
pared by  the  addition  of  sufficient  cane  or  beet  sugar  to  give  a  syrupy 
consistency.  They  may  be  preserved  by  heat,  cold  storage,  or  sodium 
benzoate,  or  by  very  high  sugar  content  (above  70  per  cent). 

A  number  of  these  were  used  in  the  preparation  of  water  ices. 
While  they  were  fairly  satisfactory  in  most  cases,  their  high  sugar 
content  made  considerable  dilution  with  water  necessary  in  order  not 
to  depress  the  freezing  point  of  the  water  ice  too  greatly  and  at  the 
same  time  maintain  the  proper  balance  between  the  sugars. 

Blackberry  and  loganberry  syrups  were  found  particularly  good 
in  flavor  and  color;  strawberry  syrup  possessed  a  pronounced  fresh 
berry  flavor  but  lacked  color.  Orange  syrup  was  quite  satisfactory  if 
not  subjected  to  prolonged  storage  (three  months  or  longer)  before 
use,  or  if  stored  at  32°  F  or  a  lower  temperature.  In  freezing  storage 
(zero  to  10°  F),  orange  syrup  retained  its  flavor  for  more  than  three 
and  a  half  years. 

In  general,  it  was  found  that  the  fruit  syrups  diluted  with  three 
volumes  of  water  to  one  volume  of  syrup  could  be  used  to  replace  the 
fresh  juices  in  the  formulas  previously  given.  See  pages  27-30.  How- 
ever, not  less  than  6  quarts  of  the  diluted  syrups  should  be  used  with 
basic  mix  to  give  5  gallons. 


BUL.  434]  THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES  33 


THE    USE   OF    FRUITS   IN   OTHER    FROZEN    DESSERTS   AND 
SPECIALTIES 

There  are  several  other  frozen  desserts  in  which  fruits  are  cus- 
tomarily used,  or  to  which  fruits  may  be  added  to  good  advantage. 
One  of  these,  frozen  plum  pudding,  is  very  popular  during  the  holiday 
season.  Several  others  described  below  are  worthy  of  consideration 
and  deserve  greater  popularity. 

Frozen  Plum  Pudding. — This  product  is  made  with  cream,  to 
which  are  added  various  dried  and  candied  fruits,  nuts,  and  usually 
eggs.  It  is  a  very  rich  dessert,  but  is  in  demand  for  the  Thanksgiving 
and  Christmas  holiday  dinners.     There  are  a  number  of  formulas,  of 

which,  the  following  is  typical  :13 

5  to  10  dozen  egg  yolks 
1  pound  cocoa 

4  pounds  cherries  and  assorted  fruits 

1  to  2  pounds  raisins 

2  pounds  figs  (dry) 

1  pound  walnut  meats 

3  tablespoonfuls  ground  cinnamon 
%  teaspoonful  ground  cloves. 

45  pounds  of  standard  or  high  fat  mix. 

(Spices  should  be  stirred  into  the  fruits  before  adding  to  the  cream.) 

Beat  the  egg  yolks  with  the  mix  (1  dozen  egg  yolks  to  1  quart  of 
mix),  heat  slowly  to  145°  F,  and  add  to  the  remainder  of  the  mix. 
Add  the  mixture  of  fruits,  nuts,  chocolate,  and  spices  during  freezing. 

Nesselrode  Pudding. — A  satisfactory  formula  in  commercial  use  is 
as  follows: 

1  pound  assorted  fruit 

6  pounds  maraschino  cherries 

2  pounds  pineapple 

6  pounds  candied  cherries 

4  pounds  raisins 

4  pounds  macaroons 

4  pounds  almonds 
Ground  together 

5  to  10  dozen  egg  yolks  (preparation  same  as  for  plum  pudding) 
Full  portion  vanilla 

Color,   gold 

45  pounds  standard  or  high  fat  mix. 

Tutti  Frutti  Ice  Cream  (Parfait). — There  are  many  formulas  in 
commercial  use  for  this  ice  cream,  candied  and  sweetened  crushed 
fruits  generally  being  used  instead  of  the  fresh  or  cold-pack  fruits. 


!3  This  formula  and  the  one  for  Nesselrode  pudding,  from:  Turnbow,  G.  D. 
and  L.  A.  Eaffetto.     Ice  cream.    John  Wiley  &  Sons.     (In  press.) 


34  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

The  following  formula  has  been  found  satisfactory : 
5  to  10  dozen  egg  yolks 
3  pounds  candied  cherries  or  maraschino  cherries 

2  to  3  pounds  of  candied  assorted  fruits 

3  pounds  pineapple 
Full  portion  of  vanilla 

45  pounds  of  standard  or  high  fat  mix. 

The  pits  should  be  removed  from  the  assorted  fruits,  which  should 
all  be  ground  before  being  added  to  the  ice  cream.  It  is  desirable  to 
soak  the  cherries  and  other  fruits  in  the  juice  of  the  pineapple  over- 
night. This  cream  is  popular  in  bricks  and  in  combination  with  other 
creams. 

Crushed  fruit  mixtures  prepared  especially  for  use  in  tutti  frutti 
are  obtainable  and  satisfactory. 

Aufait. — Aufait  is  a  brick  ice  cream  consisting  of  layers  of  one 
or  more  kinds  of  cream  with  layers  of  fruit,  whole  or  in  large  pieces, 
between  them.  Halved  candied  figs,  whole  candied  cherries,  pieces  of 
other  candied  fruits,  various  well  drained  fruit  preserves,  and  well 
cooked  dried  figs  cut  in  half,  can  be  used  in  aufait.  The  aufait  is 
especially  good  if  one  or  more  layers  of  the  brick  consist  of  fruit  ice 
creams  such  as  orange,  strawberry,  or  pineapple. 

Lacto. — Lacto  is  made  with  skim  or  whole  milk,  soured  with  lactic 
acid  culture,  and  mixed  with  sugar  and  eggs.  Fruit  juices  may  be 
added.    The  following  formula  is  typical : 

Lacto  milk  (starter,  slightly  sour  skim  or  whole 

milk)    6  gallons 

Sugar  18  pounds 

Eggs  2  dozen 

Lemon  juice 3  pints 

Use  a  small  amount  of  stabilizer. 

Fruit  juice  or  crushed  fruit  (with  sugar  added  if 

necessary)  2  quarts 

Dissolve  the  sugar  in  the  " lacto  milk."  Beat  the  egg  whites  and 
yolks  separately.  Add  to  the  milk  and  strain  through  a  fine  screen  or 
gauze.  Add  the  fruit  juices  and  freeze.  Draw  20  per  cent  less  yield 
than  for  ice  cream. 

Fruit  Mousse. — Crushed  fruits  and  fruit  juices  are  ideally  suited 
to  use  in  this  class  of  frozen  desserts.  The  following  formula  is  typical. 
It  may  be  varied  to  suit  the  nature  of  the  fruit  and  other  conditions. 
Whip  2  gallons  of  35  per  cent  cream  and  4  pounds  of  sugar  in  the 
freezer.  Slowly  add  2y2  gallons  of  soft  ice  cream  as  drawn  from  the 
freezer.     The  mixture  should  be  whipped  just  enough  to  mix  thor- 


BUL.  434]  THE  ugE  0F  FRUITS  in  ICE  CREAM  AND  ICES  35 

oughly.  Flavor  with  1  gallon  of  fruit  pulp  or  fruit  juice  and  color  as 
desired.  This  formula  adds  more  solids  to  the  cream  and  does  not 
have  the  tendency  to  stratify  or  become  grainy,  as  is  the  case  when 
only  cream  is  whipped. 

Frozen  Fruit  Punch. — Before  the  advent  of  national  prohibition, 
frozen  fruit  punches  were  usually  prepared  with  fermented  fruit 
juices,  or  other  alcoholic  beverages  were  added.  Experiments,  how- 
ever, have  demonstrated  that  excellent  fruit  punches  can  be  made  with 
the  unfermented  juices. 

In  the  Fruit  Products  Laboratory,  the  following  formula,  among 
others,  has  proved  satisfactory : 

Orange  juice  4  quarts 

Lemon  juice  1  quart 

Grape  juice  (Concord  or  Pierce  Isabella) 3  quarts 

Water  3  gallons 

Sugar 10  pounds 

The  addition  of  approximately  2  per  cent,  that  is,  3Vi  ounces  of 
gum  tragacanth,  will  cause  the  texture  to  be  smoother  and  the  keeping 
quality  better  after  freezing. 

Other  fruit  juices  may  be  substituted  for  the  grape  juice.  If  these 
are  very  sour  juices  such  as  loganberry,  use  less  lemon  juice. 

The  combinations  of  juices  that  may  be  used  in  punch  are  numerous. 
Pineapple,  loganberry,  strawberry,  blackberry,  raspberry,  and  pome- 
granate juices  are  particularly  desirable  additions.  The  syrup  from 
cold-pack  berries  and  from  maraschino  cherries  possesses  great  flavor- 
ing power  in  fruit  punches. 

Fruit  Frappes. — A  frappe  is  an  ice  consisting  of  water,  sugar,  and 
natural  flavoring,  and  chilled  to  a  soft,  semi-frozen  consistency.  It  is 
similar  in  compositoin  to  sherbets  and  wrater  ices.  Fruit  juices  may 
be  used  to  excellent  advantage  in  this  product. 

Frozen  "Suckers." — Recently  a  specialty  known  by  the  trade  as 
" frozen  suckers"  has  appeared  on  the  market,  and  in  some  localities 
has  proved  fairly  popular.  The  product  is  prepared  by  placing 
ordinary  soda  water,  not  carbonated,  in  glass  tubes  and  freezing  solid. 
Before  freezing  a  wooden  skewer  is  inserted  in  the  liquid  to  furnish  a 
handle  for  holding  the  frozen  sucker  as  it  is  consumed.  The  tubes 
are  immersed  in  warm  water  for  a  moment  to  melt  the  ice  so  that 
the  frozen  suckers  may  be  removed.  The  suckers  are  wrapped  in 
paper  and  packed  in  ice  cream  cans  surrounded  by  salt  and  ice. 

Until  the  present,  they  have  been  made  by  diluting  with  water  such 
standard  soda  water  syrups  as  ginger  ale  and  the  various  imitation 
fruit  syrups,  such  as  orange,  lemon,  grape,  strawberry,  etc. 


36  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

Experiments  by  J.  H.  Irish  of  the  Fruit  Products  Laboratory  with 
fruit  juices  and  fruit  syrups  diluted  with  water  evidenced  their 
superiority  in  flavor  to  the  imitation  fruit  products  for  the  prepara- 
tion of  pure  fruit  frozen  suckers. 

The  sugar  content  of  the  juices  or  syrup  must  not  be  greater  than 
about  15  per  cent — liquids  testing  about  12°  Balling  gave  the  best 
results.  If  too  high  in  solids,  that  is,  "too  sweet,"  the  product  either 
will  not  solidify  or  will  be  soft.  If  too  dilute,  it  will  be  too  hard  when 
frozen  and  will  lack  flavor. 

That  the  frozen  suckers  made  from  artificially  flavored  and  colored 
imitation  fruit  have  not  proved  very  popular  is  due,  no  doubt,  to  the 
fact  that  they  are  imitation  rather  than  real  fruit  juices.  Frozen 
fruit  juices  of  good  quality  should  prove  popular,  particularly  among 
school  children.  An  orange  product  of  this  sort  could  probably  be 
introduced  in  the  schools  with  very  little  difficulty. 


SUMMARY 

Investigations  have  been  conducted  cooperatively  during  the  past 
three  years  by  the  Dairy  Industry  Division  and  the  Fruit  Products 
.Laboratory  of  the  University  of  California  on  the  use  of  fresh  fruits 
and  various  fruit  products  in  ice  cream,  water  ices,  and  frozen 
specialties.     The  following  are  the  more  important  results. 

1.  Most  commercial  manufacturers  use  too  small  a  proportion  of 
fruit  in  fruit  ice  cream  and  ices.  Furthermore,  the  state  legal 
minimum  of  3  per  cent  fruit  in  fruit  ice  creams  is  altogether  too  low, 
except  for  fruit  products  that  contain  a  large  amount  of  added 
artificial  flavor. 

2.  A  basic  ice  cream  mix  containing  about  40-41  per  cent  solids 
gave  better  results  with  fruits  than  did  a  mix  of  about  35  per  cent 
solids;  the  texture  was  smoother  and  the  flavor  richer. 

3.  Satisfactory  formulas  were  developed  for  the  preparation  of 
fresh  apricot,  avocado,  banana,  fig,  peach,  pear,  and  berry  ice  creams, 
the  principal  improvement  over  previously  existing  formulas  being 
the  use  of  a  larger  proportion  of  fruit.  Avocados,  Calimyrna  figs, 
and  persimmons  gave  exceptionally  good  ice  creams  and  indications 
of  unusual  commercial  promise.  Most  of  the  canning  and  drying 
varieties  of  peaches  lacked  flavor  and  were  not  nearly  so  satisfactory 
as  some  of  the  more  highly  flavored,  soft,  table  varieties. 

Not  less  than  four  pounds  of  fresh  strawberries  to  45  pounds  of 
basic  mix  was  necessary  for  a  good  strawberry  ice  cream. 


BUL.  434]  THE  USE  OF  FRUITS  IN  ICE  CREAM  AND  ICES  37 

4.  Properly  prepared  and  stored  cold-pack  fruits  were  found  to  be 
approximately  equal  to  the  fresh  for  use  in  ice  cream  and  water  ices. 
Sealed  were  much  better  than  open  containers  for  the  storage  of  cold- 
pack  fruits.  Economical  and  satisfactory  methods  of  cold  packing 
and  storing  fresh  fruits  were  developed. 

5.  Unexpectedly,  it  was  found  that  the  lowest  and  least  costly 
grade  of  commercially  canned  fruits,  namely  Solid  Pack  Pie  Grade, 
is  the  most  satisfactory  grade  for  use  in  ice  creams  or  ices.  Canned 
figs,  in  particular,  gave  an  excellent  ice  cream  which  has  proved 
popular  when  placed  on  the  market.  Apricots  were  also  very  satis- 
factory. Canned  peaches  lacked  flavor.  Bartlett  pears  gave  a  fairly 
satisfactory  ice  cream  of  mild  flavor. 

6.  Preserves  and  jams  were  not  very  satisfactory  because  they  were 
too  sweet  and  too  costly.  Their  high  sugar  content  reduced  the  freez- 
ing point  and  caused  the  ice  cream  to  be  soft. 

7.  Methods  of  preparing  and  preserving  as  well  as  using  maras- 
chino cherries  were  studied. 

8.  Bottled  fruit  juices,  concentrates,  and  syrups  were  used  experi- 
mentally in  ice  cream  and  ices  and  satisfactory  formulas  developed 
for  these  products  made  from  suitable  fruits.  Concentrates  are 
convenient  to  store  and  use,  but  unfortunately  most  of  those  that 
have  thus  far  been  produced  commercially  are  lacking  in  flavor,  or 
deteriorate  very  rapidly  during  storage  at  room  temperature. 

9.  Broken  pieces  and  ground  or  chopped  candied  fruits,  by- 
products of  candied  fruit  factories,  were  found  very  satisfactory  for 
use  in  specialties  such  as  tutti  frutti  ice  cream. 

10.  Prunes  gave  the  best  results  of  all  dried  fruit  studied,  and 
because  of  their  health  value,  ice  cream  made  with  prunes  should  have 
great  commercial  possibilities.  Raisin  ice  cream  made  with  Muscat 
raisins  was  excellent ;  that  made  with  Thompson  seedless  was  decidedly 
lacking  in  flavor.  Other  dried  fruits  are  so  much  inferior  to  the 
canned  fruits  that  their  use  is  not  recommended  unless  the  canned  is 
unobtainable. 

11.  Puddings,  tutti  frutti,  aufait,  lacto,  mousses,  punch,  and 
frappes,  all  contain  fruit  or  are  improved  by  its  addition.  Frozen 
"suckers"  made  with  fruit  juices  were  very  much  superior  to  those 
made  with  the  imitation  fruit  or  artificially  colored  and  flavored 
liquids  heretofore  used  commercially. 


38  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 


ACKNOWLEDGMENTS 

The  authors  desire  to  express  their  appreciation  to  J.  H.  Irish, 
Assistant  Chemist  in  the  Fruit  Products  Laboratory;  to  H.  A.  Spil- 
man  of  the  Dairy  Industry  Division;  and  to  E.  E.  Brown,  Student 
Assistant,  for  valuable  assistance  in  these  investigations.  We  also 
desire  to  thank  Wilbur  Thomas  and  Albert  Ernst  of  Hage's  Ice 
Cream  Co.,  San  Diego,  for  cooperation  in  commercial  scale  experi- 
ments and  for  suggestions  and  corrections  offered  during  preparation 
of  the  manuscript. 


STATION  PUBLICATIONS  AVAILABLE   FOR  FREE   DISTRIBUTION 


No. 

275.  The     Cultivation     of     Belladonna     in 

California. 

276.  The  Pomegranate. 

277.  Sudan    Grass. 

278.  Grain    Sorghums. 

279.  Irrigation   of  Rice  in   California. 
283.  The  Olive  Insects  of  California. 
294.   Bean   Culture  in    California. 

304.  A  Study  of  the  Effects  of  Freezes  on 

Citrus    in    California. 
310.   Plum    Pollination. 

312.  Mariout  Barley. 

313.  Pruning      Young      Deciduous      Fruit 

Trees. 
319.   Caprifigs    and    Caprification. 
324.   Storage  of   Perishable  Fruit  at  Freez- 
ing Temperatures. 
825.  Rice     Irrigation     Measurements     and 

Experiments    in    Sacramento   Valley, 

1914-1919. 
328.   Prune   Growing   in    California. 
331.   Phylloxera-Resistant    Stocks. 
835.   Cocoanut   Meal    as    a    Feed    for   Dairy 

Cows   and    Other   Livestock. 
339.  The    Relative    Cost    of    Making    Logs 

from    Small   and  Large  Timber. 
840.  Control     of     the     Pocket     Gopher     in 

California. 

343.  Cheese    Pests    and    Their    Control. 

344.  Cold    Storage   as    an   Aid   to   the   Mar- 

keting of  PlumB. 

346.  Almond    Pollination. 

347.  The  Control  of  Red  Spiders  in  Decid- 

uous Orchards. 

348.  Pruning  Young  Olive  Trees. 

349.  A     Study    of    Sidedraft    and    Tractor 

Hitches. 

350.  Agriculture      in      Cut-over      Redwood 

Lands. 

352.  Further  Experiments  in  Plum  Pollina- 

tion. 

353.  Bovine   Infectious   Abortion. 

354.  Results  of  Rice  Experiments  in   1922. 

357.  A    Self-mixing    Dusting    Machine    for 

Applying      Dry      Insecticides      and 
Fungicides. 

358.  Black    Measles,     Water    Berries,     and 

Related  Vine  Troubles. 

361.  Preliminary   Yield    Tables    for    Second 

Growth   Redwood. 

362.  Dust  and  the  Tractor  Engine. 

363.  The  Pruning  of  Citrus  Trees  in  Cali- 

fornia. 

364.  Fungicidal    Dusts    for   the    Control    of 

Bunt. 

365.  Avocado  Culture  in  California. 

366.  Turkish  Tobacco  Culture,   Curing  and 

Marketing. 
867.  Methods  of  Harvesting  and  Irrigation 
in   Relation  of  Mouldy  Walnuts. 

368.  Bacterial  Decomposition  of  Olives  dur- 

ing Pickling. 

369.  Comparison     of     Woods     for     Butter 

Boxes. 

370.  Browning  of  Yellow  Newtown  Apples. 

371.  The    Relative    Cost   of    Yarding    Small 

and   Large  Timber. 

372.  The  Cost  of  Producing  Market  Milk  and 

Butterfat  on  246  California  Dairies. 

373.  Pear    Pollination. 

374.  A  Survey  of  Orchard  Practices  in  the 

Citrus    Industry  of    Southern    Cali- 
fornia. 

375.  Results   of   Rice   Experiments   at   Cor- 

tena,    1923. 

376.  Sun-Drying  and  Dehydration  of  Wal- 

nuts. 

377.  The  Cold    Storage  of   Pears. 

379.  Walnut   Culture   in   California. 

380.  Growth    of    Eucalyptus    in    California 

Plantations. 

381.  Growing     and     Handling     Asparagus 

Crowns. 


BULLETINS 
No. 


382. 
383. 
385. 


387. 
388. 


390. 

391. 

392. 
393. 
394. 

395. 
396. 

397. 

398. 
399. 


400. 
401. 

402. 
403. 
404. 
405. 
406. 
407. 


408. 
409. 


410. 
411. 
412. 

413. 

414. 

415. 
416. 

417. 

418. 

419. 
420. 

421. 

422. 

423. 

424. 

425. 
426. 

427. 

428. 


Pumping  for  Drainage  in  the  San 
Joaquin    Valley,    California. 

Monilia  Blossom  Blight  (Brown  Rot) 
of  Apricot. 

Pollination    of    the    Sweet   Cherry. 

Pruning  Bearing  Deciduous  Fruit 
Trees. 

Fig  Smut. 

The  Principles  and  Practice  of  Sun- 
drying  Fruit. 

Berseem   or   Egyptian    Clover. 

Harvesting  and  Packing  Grapes  in 
California. 

Machines  for  Coating  Seed  Wheat  with 
Copper    Carbonate    Dust. 

Fruit    Juice    Concentrates. 

Crop  Sequences  at  Davis. 

Cereal  Hay  Production  in  California. 
Feeding  Trials  with  Cereal  Hay. 

Bark   Diseases   of  Citrus  Trees. 

The  Mat  Bean  (Phaseolus  aconitifo- 
lius). 

Manufacture  of  Roquefort  Type  Cheese 
from   Goat's   Milk. 

Orchard  Heating  in  California. 

The  Blackberry  Mite,  the  Cause  of 
Redberry  Disease  of  the  Himalaya 
Blackberry,    and    its    Control. 

The  Utilization  of  Surplus  Plums. 

Cost  of  Work  Horses  on  California 
Farms. 

The  Codling  Moth  in  Walnuts. 

Farm-Accounting  Associations. 

The  Dehydration  of  Prunes. 

Citrus  Culture  in  Central  California. 

Stationary  Spray  Plants  in  California. 

Yield,  Stand  and  Volume  Tables  for 
White  Fir  in  the  California  Pine 
Region. 

Alternaria  Rot  of  Lemons. 

The  Digestibility  of  Certain  Fruit  By- 
products as  Determined  for  Rumi- 
nants. 

Factors  Affecting  the  Quality  of  Fresh 
Asparagus  after  it  is  Harvested. 

Paradichlorobenzene  as  a  Soil  Fumi- 
gant. 

A  Study  of  the  Relative  Values  of  Cer- 
tain Root  Crops  and  Salmon  Oil  as 
Sources  of  Vitamin  A  for  Poultry. 

The  California  Poultry  Industry;  a 
Statistical   Study. 

Planting  and  Thinning  Distances  for 
Deciduous  Fruit  Trees. 

The  Tractor  on  California  Farms. 

Culture  of  the  Oriental  Persimmon 
in    California. 

Poultry  Feeding:  Principles  and 
Practice. 

A  Study  of  Various  Rations  for 
Finishing  Range  Calves  as  Baby 
Beeves. 

Economic  Aspects  of  the  Cantaloupe 
Industry. 

Rice  and  Rice  By-products  as  Feeds 
for   Fattening   Swine. 

Beef   Cattle   Feeding  Trials,    1921-24. 

Cost  of  Producing  Almonds  in  Cali- 
fornia ;  a  Progress  Report. 

Apricots  (Series  on  California  Crops 
and  Prices) . 

The  Relation  of  Rate  of  Maturity  to 
Egg  Production. 

Apple   Growing   in    California. 

Apple  Pollination  Studies  in 
fornia. 

The  Value  of  Orange  Pulp  for  Milk 
Production. 

The  Relation  of  Maturity  of 
fornia  Plums  to  Shipping 
Dessert    Quality. 


Cali- 


Cali- 
and 


No. 

87.  Alfalfa. 
117.  The    Selection    and    Cost    of    a    Small 

Pumping  Plant. 
127.  House   Fumigation. 
129.  The  Control  of  Citrus   Insects. 
136.   Melilotus    indica    as    a    Green-Manure 

Crop  for  California. 
144.  Oidium    or    Powdery    Mildew    of    the 

Vine. 
157.  Control  of  the  Pear  Scab. 
160.   Lettuce  Growing  in  California. 
164.   Small  Fruit  Culture  in  California. 
166.   The  County   Farm  Bureau. 
170.   Fertilizing     California     Soils     for     the 

1918   Crop. 
173.  The    Construction    of    the    Wood-Hoop 

Silo. 

178.  The   Packing  of  Apples   in    California. 

179.  Factors    of    Importance    in    Producing 

Milk  of  Low  Bacterial  Count. 
190.  Agriculture  Clubs  in  California. 
199.   Onion    Growing   in    California. 

202.  County    Organizations   for   Rural    Fire 

Control. 

203.  Peat   as   a   Manure    Substitute. 

209.  The  Function  of  the  Farm   Bureau. 

210.  Suggestions  to  the  Settler  in  California. 
212.   Salvaging    Rain-Damaged    Prunes. 
215.   Feeding  Dairy  Cows  in  California. 
217.  Methods   for   Marketing  Vegetables   in 

California. 
220.   Unfermented   Fruit  Juices. 
228.  Vineyard  Irrigation  in  Arid  Climates. 

230.  Testing  Milk,    Cream,    and   Skim   Milk 

for  Butterfat. 

231.  The    Home    Vineyard. 

232.  Harvesting    and    Handling    California 

Cherries    for    Eastern    Shipment. 

234.  Winter  Injury  to  Young  Walnut  Trees 

during  1921-22. 

235.  Soil     Analysis     and     Soil     and     Plant 

Inter-relations. 

236.  The     Common     Hawks     and     Owls    of 

California    from    the    Standpoint    of 
the  Rancher. 

237.  Directions  for  the  Tanning  and  Dress- 

ing of  Furs. 

238.  The  Apricot  in   California. 

239.  Harvesting     and     Handling     Apricots 

and  Plums  for  Eastern  Shipment. 

240.  Harvesting    and    Handling    Pears    for 

Eastern   Shipment. 

241.  Harvesting  and  Handling  Peaches  for 

Eastern   Shipment. 

243.  Marmalade  Juice  and  Jelly  Juice  from 

Citrus  Fruits. 

244.  Central  Wire  Bracing  for  Fruit  Trees. 

245.  Vine   Pruning  Systems. 

247.  Colonization    and    Rural   Development. 

248.  Some    Common    Errors    in    Vine  Prun- 

ing and  Their  Remedies. 

249.  Replacing    Missing    Vines. 

250.  Measurement   of    Irrigation   Water   on 

the  Farm. 

252.  Supports  for  Vines. 

253.  Vineyard  Plans. 

254.  The  Use  of  Artificial  Light  to  Increase 

Winter    Egg    Production. 


CIRCULARS 
No. 


255. 

256. 
257. 
258. 
259. 
261. 
262. 
263. 
264. 

265. 
266. 

267. 

269. 
270. 
272. 

273. 
274. 

276. 
277. 

278. 

279. 

281. 


282. 

283. 
284. 
285. 
286. 
287. 
288. 
289. 
290. 
291. 

292. 
293. 
294. 
295. 


298. 

299. 
300. 
301. 
302. 
303. 

304. 
305. 
306. 

307. 
308. 
309. 


Leguminous  Plants  as  Organic  Fertil- 
izer   in    California    Agriculture. 

The   Control   of  Wild   Morning   Glory. 

The  Small-Seeded  Horse  Bean. 

Thinning   Deciduous   Fruits. 

Pear  By-products. 

Sewing  Grain  Sacks. 

Cabbage  Growing  in   California. 

Tomato  Production  in  California. 

Preliminary  Essentials  to  Bovine 
Tuberculosis  Control. 

Plant   Disease   and   Pest  Control. 

Analyzing  the  Citrus  Orchard  by 
Means   of    Simple   Tree   Records. 

The  Tendency  of  Tractors  to  Rise  in 
Front;    Causes  and  Remedies. 

An  Orchard  Brush  Burner. 

A  Farm  Septic  Tank. 

California  Farm  Tenancy  and  Methods 
of  Leasing. 

Saving  the  Gophered  Citrus  Tree. 

Fusarium  Wilt  of  Tomato  and  its  Con- 
trol by  Means  of  Resistant  Varieties. 

Home  Canning. 

Head,  Cane,  and  Cordon  Pruning  of 
Vines. 

Olive  Pickling  in  Mediterranean  Coun- 
tries. 

The  Preparation  and  Refining  of  Olive 
Oil   in    Southern    Europe. 

The  Results  of  a  Survey  to  Determine 
the  Cost  of  Producing  Beef  in  Cali- 
fornia. 

Prevention  of  Insect  Attack  on  Stored 
Grain. 

Fertilizing  Citrus  Trees  in  California. 

The   Almond   in   California. 

Sweet  Potato  Production  in  California. 

Milk  Houses  for  California  Dairies. 

Potato   Production   in   California. 

Phylloxera   Resistant  Vineyards. 

Oak  Fungus  in  Orchard  Trees. 

The  Tangier  Pea. 

Blackhead  and  Other  Causes  of  Loss 
of  Turkeys  in   California. 

Alkali   Soils. 

The    Basis    of   Grape    Standardization. 

Propagation   of  Deciduous   Fruits. 

The  Growing  and  Handling  of  Head 
Lettuce  in   California. 

Control  of  the  California  Ground 
Squirrel. 

The  Possibilities  and  Limitations  of 
Cooperative  Marketing. 

Poultry   Breeding   Records. 

Coccidiosis  of  Chickens. 

Buckeye  Poisoning  of  the  Honey  Bee. 

The   Sugar  Beet  in   California. 

A  Promising  Remedy  for  Black  Measles 
of  the  Vine. 

Drainage  on  the  Farm. 

Liming  the  Soil. 

A  General  Purpose  Soil  Auger  and  its 
Use  on  the  Farm. 

American    Foulbrood   and  its   Control. 

Cantaloupe  Production  in  California. 

Fruit  Tree  and   Orchard  Judging. 


The  publications  listed  above  may  be  had  by  addressing 

College  of  Agriculture, 

University  of  California, 

Berkeley,  California. 

12m-9.'27 


